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Discussion Starter #1
Before a few days ago my car would start and run fairly well but somehow that all changed after the last ice/snow storm. Originally the only time the engine would cut out for a just split second was when taking one particular on-ramp that turns you around 180 degrees before ending with a fairly steep climb. The difference between that cutting out and what began happening more recently is that when it cuts out the check engine light comes on but quickly disappears when the engine regains power. Otherwise I have no check engine light whatsoever.

I began to think that my car was having a new issue a little over a month ago when I was on one of my many 50 mile trips. As I was cruising down the highway I noticed the tach jump from 2K to nearly 4K with the CEL on before the engine stalled and died. I coasted to a stop onto the shoulder and gave the car a quick moment before firing her right back up. I didn't want to be late to the appointment I had to get 2 more new tires and all I could figure was that maybe driving with a stock spare up front with 18" rims was somehow taxing the tranny. Another 10 miles later after taking my exit the engine did the exact same thing but I managed to coast into a parking spot. Just in case, I wiggled the crank position sensor connector before firing her back up and making it the rest of the way to the tire shop.

While it didn't feel like the tranny had shifted from OD to 3rd I couldn't be certain because of the issue I was having with my tires falling apart. I still guessed maybe I was a little low on tranny fluid and it was over a half a quart low. Topping it off seemed to help because I didn't have any more issues for several weeks or hundreds of miles. It didn't start acting up again until I made it to Abilene to spend a few weeks in my parent's home for the holidays.

This time the only time the engine would cut out was randomly whenever I was moving from a stop. The CEL would still pop up during the event but this time there wasn't any amount of surging. Feathering the throttle seemed to help this bucking bronco but even if I just maintained the gas it would eventually work itself out and away I went. Not once did it die or really worry me that I wasn't going to make it to the house. So, now we're up to what happened this week.

If you somehow don't know we had some nasty weather over the weekend and on Monday I needed to remove the snow and ice from the exterior of the car before running an errand. I started the car no problem and proceeded to brush and scrape away all of the snow and ice. Maybe 5 or 10 seconds into the work the car began cutting out and regaining power almost every 5 seconds. I continued working on the car figuring it would work itself out but after over a dozen or so hiccups it finally died.

Trying to start the car was unsuccessful especially after just a few tries because the battery was already drained. There's not much that can be done to diagnose this issue with a dead battery so I tried jumping the car with the supposedly charged marine battery that my father had hanging around. My dad insisted that the battery was good and charged but I decided to find the battery tender and try using it. Unfortunately where that tender had been in my father's workshop is where the roof decided to leak. This isn't my house so I wasn't going to risk plugging it in until either it dried out by the next day or whenever my dad said it was fine.

So, I trickle charged the marine battery overnight only to have to instead run a long power cable out to my car to give my battery a quick charge because my dad's marine battery just cannot seem to give my car any good power. The starter engages just fine but there didn't seem to be any fuel making it to the engine. I cannot hear the fuel pump priming when first turning the key but I do hear the engine fan coming on and running probably on high speed. That made me assume that my CCRM or IRCM had hit the bucket and from what I read here at the forums in the past I figured my only course of action was to add my own relay system.

Later that day, yesterday, I bought 4 relays and late last night I got to looking at the EVTM and realized that there's more than relays in the CCRM. Without somehow reusing the solid state units to interface with the PCM I didn't see any way to go "poorboy style" unless all I was needing was the fan and the fuel pump to be controlled by a switch in the dash. How to make sure the A/C was properly engaging or choosing any other fan speed other than high is probably beyond my current skill set. Before going to bed I had to check and see if these CCRMs were really that impossible to find at parts stores and luckily the first place I looked, Advance, had some re-manufactured units which made me glad because even though they never keep them in stock I could possibly get one by tomorrow.

It's probably a good thing I didn't order one right away because after reading some more topics here and trying to use a multimeter on the CCRM I'm more inclined to believe that my PCM has bit the dust. Reason being because when you turn the key before starting there is no CEL but the CEL did flash when the engine managed to almost start. Upon a few more tries the engine did start and run a few times for a few moments before cutting out again and dying with the CEL only showing up during the hiccups but staying off after the death. You can actually hear the pump priming during the hiccups.

While checking for fuel at the fuel rail there was a longer than normal pause after turning the key and still after I had already began standing at the front of the car. This time I heard the CCRM make about 3 or 4 clicks before turning the fan on full speed. Plenty of fuel squirted out onto my un-gloved hand which proves that the fuel pump is running at some point. When I tried starting the car one last time it ran a little longer than the last few times but when the engine cuts out it's becoming more obvious that I can hear the CCRM clicking.

My conclusion is that either I need a new PCM or perhaps still just the CCRM with the PCM being more likely because of the lack of a pre-startup CEL.

I did pull the kick panel and put my hands on the PCM harness just to make sure there wasn't a leak above it and everything was dry as a desert. The carpet near the foot of the seat however did become soaked with water after a heavy rainstorm almost 2 months ago but it was fine during the last one.

I would like to use the multimeter more and be able to give better descriptions of the voltages at each point but after trying to check the harness for the CCRM I don't know how people can probe the wires without having to take the connector off or cutting into the wires which would require sealing.

When it comes to prior maintenance I must already throw out the fact that because I did my PI intake swap with some parts from a boneyard I do have a few issues with some of those parts. The IAC valve or TPS may definitely need replacing because I used to have a high idle when stopped and the car would reach 35 mph without needing me to touch the throttle. My mileage is terrible considering all of the work I've put into the car with my average being 17 mpg and that's 90% highway miles. There is an exhaust leak at the EGR tube adapter that is audible even though it's as hooked up as much I can get with flat threads. There had been a EGR related CEL but that went away after the wire loom that happened to be touching the EGV valve melted itself to it with the state of the plastic emissions line inside left unknown until I cut it all open but I can patch that at anytime with parts on hand.

Beyond the intake swap my car has had a used Jerry Chip for about 7 years. If I had some stock spark plugs hanging around I'd try removing the chip and seeing if that's the cause for the PCM going bad. The catalytic converters are hollow and my upstream o2 sensors were replaced when I did the intake swap over a year ago. The MAFS was also replaced right after the intake swap when it became apparent that was the cause for my car dying when warmed up before the swap. My K&N air filter is filthy but I doubt that's causing my car not to run.

Nah, I reckon that after 20 years of use the PCM is ready for its replacement. I'd appreciate it if anybody could confirm or correct my educated guess. Thanks for reading one of my novels.
 

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1997 Thunderbird 4.6, 1998 Mark VIII LSC
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Hmmm.. certainly possible. A couple questions for clarification.

Any DTCs in memory or pending?

You mention you moved the key to the on position and there was a bit of a delay in the usual series of relay clicks from the CCRM - long enough for you to have gotten out of the car after having turned the key on, and made your way to the front of the car? And when you checked for fuel pressure, there was none until just after the CCRM clicked and engaged the pump? You also say you heard the CCRM clicking when the engine died after you checked for fuel pressure?

All of this COULD be a PCM issue... but it could also be something else - like an intermittent ground. To be certain additional pinpoint tests need to be performed. E.G. monitoring fuel pressure and using a noid light to verify spark as the engine runs - then observing if either/which one fails when the engine dies. Also keep in mind the PCM gets power through the CCRM - so a flaky relay in the CCRM could be causing all of this as well.

BTW there's no reason you can't remove a chip with only different spark plugs and a PI intake. As long as the heads/injectors/MAF are stock, you can pull the chip.
 

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Discussion Starter #3
Thanks Brandon!

Hmmm.. certainly possible. A couple questions for clarification.

Any DTCs in memory or pending?
That's exactly what I was planning to have scanned at a parts store when I was going to run an errand.

You mention you moved the key to the on position and there was a bit of a delay in the usual series of relay clicks from the CCRM - long enough for you to have gotten out of the car after having turned the key on, and made your way to the front of the car?
Yes but it only happened like that one time. I usually hear the clicking right after I turn the key but not every time unless I just tuned my ears to the sound.

And when you checked for fuel pressure, there was none until just after the CCRM clicked and engaged the pump?
I don't own a pressure gauge so all I did was poke the schrader valve before and after I performed that test and each time fuel squirted out. While I did hear clicking I couldn't hear the fuel pump still.

You also say you heard the CCRM clicking when the engine died after you checked for fuel pressure?
No, the clicking so far has only been heard before startup and during the hiccups.


All of this COULD be a PCM issue... but it could also be something else - like an intermittent ground.
Yeah, I keep hoping my issues are always just a bad ground which is why I bought the EVTM but so far it ends up being the components themselves.

To be certain additional pinpoint tests need to be performed. E.G. monitoring fuel pressure and using a noid light to verify spark as the engine runs - then observing if either/which one fails when the engine dies.
I've been meaning to look up the cost of a simple fuel pressure gauge and noid light. Hopefully not too much because I'm living on a rather limited budget until the end of February.

Also keep in mind the PCM gets power through the CCRM - so a flaky relay in the CCRM could be causing all of this as well.
When I look at the EVTM I see the PCM getting 1 12v power source directly from the 15FL 20A fuse, the same place the CCRM gets most of its power. The other 2 sources are from the CCRM but that power also goes to the tranny and ignition system. Which one makes the PCM run enough to show a prestartup CEL?

Then there's that R/LG wire that appears to imply that the ignition switch is between 3FL 20A fuse and the CCRM and the rest of the ignition system. I'm 100% certain my ignition switch and cylinder are in need of replacement and I wouldn't be surprised if it's the main culprit. I over-tightened the screw for the harness when I installed my car alarm and I had a dream the whole switch will fall to pieces the next time I remove the harness. I wonder if the ignition switch would prevent the prestartup CEL.

BTW there's no reason you can't remove a chip with only different spark plugs and a PI intake. As long as the heads/injectors/MAF are stock, you can pull the chip.
Oh, I was afraid the colder plugs and advanced timing could throw it off too much even with the octane plug removed.
 

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Ignition switch certainly can do odd things if it's not 100%. There are some weird "intermediate" things that happen as the ignition is moved between ON and OFF - for example, I can kill the engine by rotating the key out of ON towards OFF ever so slightly - but all the electronics in the car stay on. Slightly further towards off, some of the electronics die and the blower motor starts running on high. Further off and it all shuts down.

I don't have my EVTM with me now but I don't think there's enough information in it to determine how the PCM operates based on which power sources are active.

As far as a fuel pressure gauge, you should be able to find one for around $30 (or at least the one I picked up at AutoZone was something like that).

I'll admit though - I'm not certain about that lack of an SES light at KOEO. Normally it should come on as soon as the key goes to ON and the PCM starts, then it will flash quickly once then remain on until you crank. It should go out during cranking (indicating good CKPS signal), then stay off after startup.

In short... there are a lot of tests that can be done to help localize the issue. I prefer to avoid throwing parts at a problem until I've more or less cornered myself in. Right now I'm suspicious of grounding/corrosion, electrical shorts, CCRM and the ignition switch. It's not that PCMs don't go bad, but I'd like to rule out some of the other common problems/possibilities before coming to the conclusion it needs to be replaced. If you had a good spare on hand it'd be another thing, but since it doesn't look like you do...
 

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Discussion Starter #5
For the sake of troubleshooting I'll be going to the junkyard to pick up the lowest mileage CCRM and PCM if I can find a A5W0. Maybe I'll pick up an ignition switch too but I think I might rather just buy the new one asap because it's fairly cheap. I suppose a possibility would be to wire some power to the PCM to see if it is the CCRM.
 

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Sounds like a good enough place to start.
 

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Discussion Starter #7
I haven't had any luck with the junkyard because they decided to stay closed the Saturday after the 1st so I'm not able to try again until this Saturday. I did however try a few other things and while I've taken a step forward I still feel like I'm 2 steps back.

Yesterday I thought I had the car almost figured out. It would seem that resetting the PCM by pulling the fuse would allow the car to act normal when you first turn the key with the fuel pump priming and the CEL popping up. I tried banging on everything I could around the engine bay and wiggled as many wires and connections as I could but I couldn't get the car to stall that way. I closed the hood more gently but still had to give it some force and luckily the engine didn't stall. I turned the car off and restarted it a few times and then drove it up the block thinking that as long as I didn't hit a hard bump I might be okay. Then I took the car to Advance to get the codes read but that ended up being a waste of time.

I had no problem getting to the store but they had had their code reader stolen by someone in the past so they no longer ran codes leaving me S.O.L.. Luckily I took a left turn leaving the store to drive through a few blocks of residential housing to get to the closest O'Reilly's but I didn't get but a block away before the engine stalled while trying to cross the intersection. This time resetting the PCM did not help the prestartup CEL to return. I had no choice but to call for a tow and have it sent back to my parent's.

I had already ordered a CCRM through O'Reilly's days ago but it didn't come in until this morning. I was happy to see the return of the prestartup CEL but this time not only did the fan power up but so did the fuel pump. I'd be even happier if the car started up but this thing just has the fuel pump constantly pumping with the fan running for no good reason. Car cranks just fine but it just won't fire up. This would make me think it was the temp sensor for the PCM but keep in mind I did replace it about 6 or 7 years ago.

After reviewing the EVTM even more I decided that I needed to find this 10A in-line fuse for the fan motor named C119 but I cannot figure out where it is in the vehicle. Mystery fuses aren't new to me after finding the separate fuse for the blower fan beside the fuse box inside the cabin but if I keep searching the forums I may find it before the next morning. I would assume it would be close to the PCM but I'm having no good luck at the moment. I love any excuse to go out to my car because it hides the times I want to smoke a bit.

I did come across a message thread at a random site after trying to use Google and came across this

Ford Thunderbird Questions - 1997/Thunderbird/V8. If the electric radiator fan comes on when engine... - CarGurus

This makes me feel that maybe perhaps the continuity testing I will be doing tomorrow will be pointless but like I said I like getting outside when I can whenever weather is permitting. I just hope I do find a PCM with a A5W0 code at the junkyard otherwise I'll be spending another $150.
 

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Do the fan and fuel pump run continuously when turning the key on? Mine does.

If so, it's the PCM, according to RobertP. Hopefully, I will find out tonight if a new one fixes my issue.

Al
 

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Discussion Starter #9
Do the fan and fuel pump run continuously when turning the key on? Mine does.

If so, it's the PCM, according to RobertP. Hopefully, I will find out tonight if a new one fixes my issue.

Al
Yes, exactly!

I'll still poke around with a multimeter after I go do some aquarium work for money. It's just going to be a long bike ride with a fairly heavy backpack.
 

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... my dad's marine battery just cannot seem to give my car any good power. The starter engages just fine but there didn't seem to be any fuel making it to the engine. I cannot hear the fuel pump priming when first turning the key but I do hear the engine fan coming on and running probably on high speed. That made me assume that my CCRM or IRCM had hit the bucket and from what I read here at the forums in the past I figured my only course of action was to add my own relay system.
If the starter engaged just fine, the marine battery was doing its job. That draws many times more current than anything else at startup.

The constantly running fan, the fuel pump priming problem, and the intermittent CEL are dead giveaways of problem related to the PCM.

However, that doesn't mean that the PCM itself is the problem.

The most likely cause is a bad EEC ground. This is the small wire that is connected to the negative battery cable and to the radiator support.

Before you spend another dime, please go out and make sure that the wire is undamaged, tightly connected to the negative battery cable, and that the black inline connector is plugged in.

Then unbolt it from the radiator support and clean off any corrosion on the sheetmetal and on the ring terminal.

Tighten it back down, then see what happens. If you still get nothing, then I would proceed to testing for power and ground at the PCM connector in the kick panel.

Only after verifying that would I think about the PCM being bad.
 

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Discussion Starter #11
If the starter engaged just fine, the marine battery was doing its job. That draws many times more current than anything else at startup.

The constantly running fan, the fuel pump priming problem, and the intermittent CEL are dead giveaways of problem related to the PCM.

However, that doesn't mean that the PCM itself is the problem.

The most likely cause is a bad EEC ground. This is the small wire that is connected to the negative battery cable and to the radiator support.

Before you spend another dime, please go out and make sure that the wire is undamaged, tightly connected to the negative battery cable, and that the black inline connector is plugged in.

Then unbolt it from the radiator support and clean off any corrosion on the sheetmetal and on the ring terminal.

Tighten it back down, then see what happens. If you still get nothing, then I would proceed to testing for power and ground at the PCM connector in the kick panel.

Only after verifying that would I think about the PCM being bad.
Thank you, Steve! Not even the marine battery had enough juice to fully engage the starter. I just keep throwing the battery tender out there with me when I'm certain the voltage is dropping. I've checked for power and ground on the CCRM side but I haven't tried the PCM side just yet. I'll be doing that tomorrow before I finally get to borrow a truck and hit the junkyard. I did manage to find a loaner scanner at Autozone and the PCM wouldn't connect.

I'll be very shocked if I have a bad connection considering that I moved the battery to the trunk and did this:





The positive side is only temporary as I'll be running an 0 gauge solid core cable from the battery to the starter and I'll be pulling the power for the car alarm from back there too. Otherwise I was going to upgrade all of my grounds to 0 gauge but I had to settle for 2 gauge for now. Every time I touch the cabling I run out of 0 gauge ring terminals before I know it. I just used 3 to complete and tighten up the trunk side after needing to replace the crappy battery terminals with quick disconnects.
 

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No offense intended, but knowing that the battery is relocated, I would look even harder at the EEC ground wire. ;)
 

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Agreed. Relocating the battery is just asking for problems. You brought the starting issue on yourself.

Al
 

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Discussion Starter #14 (Edited)
Wow, I didn't realize I'd get grief from anyone for relocating the battery. :frown2: I've been lurking around this site for quite awhile (since 2002) and I had never read anything wrong with moving the weight to the back. At the time I had some charging issues (turned out to be a bad alternator) and I wanted the battery somewhere it is exposed to less engine heat and weather while also giving me more room in the engine bay. My plan is to add a second battery when I can afford 2 new sealed batteries and an isolator. Well, I did that work over 4 months ago and I really don't think that's causing any issue now that I have a new battery terminal that can't be pulled off the post by hand.

Time to go outside and check those grounds and power wires before I head to FM 600 and hopefully find a PCM.

EDIT: Just got done checking the wires and everything checked out fine but I wish someone would tell me where to find the 10A in-line fuse that goes from the CCRM and PCM to the cooling fan. I'll look again closer to the fan but I cannot find it near the CCRM or PCM.
 

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Discussion Starter #15
I picked up 2 PCMs because the 75,566 mile one was more probably more exposed than the 102,123 mile PCM. I went ahead and installed the Jerry Chip on the lower mileage PCM and realized that installing PCMs seem to be a lot easier than taking the out. I decided to plug everything in and leave it hanging and I'd hope that the PCM didn't require being against the body to be fully grounded. It doesn't matter what I do I can only hear the fan running when I turn the key. I didn't even bother using the chip with the other PCM.

Just to rule out my cabling and wires for the sound system I will undo everything and put it as close to stock as I can.
 

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That's a drag. I was about to tell you that another ECU fixed my car, and like I said earlier, my car's symptom was the fan and fuel pump running continuously with the key on.

FYI, I have the ECU currently sitting on a pillow under the dash, so worries about grounding it.

Al
 

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Discussion Starter #17
That's a drag. I was about to tell you that another ECU fixed my car, and like I said earlier, my car's symptom was the fan and fuel pump running continuously with the key on.

FYI, I have the ECU currently sitting on a pillow under the dash, so worries about grounding it.

Al
Cool, thanks Al. Hard to imagine all 3 ECUs being bad and luckily I can return the 2 and get back my $90.
 

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Discussion Starter #18
Despite the bitter cold I still worked on the car yesterday and managed to get the battery relocation undone. By using the cables I had grounded the battery and capacitor in the trunk with I more or less finished upgrading the Big 3 to 0 gauge. Unfortunately there was no change in the car's behavior.

Considering that I had done the relocation back in June I didn't expect that to be the culprit. I was hoping it was the reason the car wouldn't shut off on the August night I replaced the alternator. This car is really becoming a mystery if relays keep on working backwards. Yesterday I did find the engine ground I added years ago disconnected but my newer bigger 0 gauge ground didn't change anything.

Next up should probably be removing the alarm after undoing the push-to-start button I added a few years ago when the original wire had an open. The alarm has been in the car for about 5 years but maybe something is shorting out. Even though I didn't arm the alarm; the alarm did go off on Friday and ran down the battery.

I had heard it going off when I came by the house but my 2 way remote wasn't going crazy and it had sound like it was coming from blocks away. I really didn't recognize the sound as being mine and I thought mine would stop after a little while but it went on for at least 7 hours while I was away from the house. I really thought that my battery was still disconnected but I was wrong.

I've got 9 days and very little money to get this done before I need to get back to school. :bangwall:
 

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I didn't mean that the relocation is a bad idea per se, and didn't mean to question your work. I just meant, if it was my car, I would first double and triple check whatever I had modified.

I would suggest getting out a multimeter and quickly checking the EEC connector. You need power and ground at Key On. I suspect the ground circuit, as I mentioned.

The alarm system is another key culprit. If you can bypass it at least temporarily, that would help.
 

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I just 're-read the whole thread and have 4 more ideas:

1. Did you ever try taking the Jerry chip off and see what happens? A bad chip could possibly act like this.

2. Did you verify that the harness you over-tightened is still intact?

3. How about the partially melted harness next to the EGR valve? I am less worried about the hose and more about the wire insulation inside. Might be good to peel back the tape just to have a quick look.

4. How we check voltages with the connections closed is to pick up some long pins and slide them in from the back side of the connector until we are sure that they are touching metal. I like the kind with the round plastic balls on the end. They are only a few bucks for like a hundred. Just bend them as needed so you can reach each one with the multimeter probes, but they don't touch each other. This is called "backprobing".
 
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