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Discussion Starter #1
Car: 1997 Ford Thunderbird 4.6L V8, pretty much loaded ~250,000 miles.

I just replaced the heater core - what a job. I removed the steering column and dashboard assy (there was no other way to get it done). I put it all back together (I think) and now the car will not run. The starter turns the engine over very well, just won't fire. The battery IS DEFINITELY good.

I'd like to think that I missed putting something back together, but I have searched high and low and all seems to be like it is supposed to be. It ran great before I did this.

The battery had been disconnected for a little over 2 weeks (I had to quit in the middle to wait on a 5-day monsoon to pass). The car has sat with a dead battery for almost a year before and it started right up then, so I can't imagine a ECM/PCM reset doing this. Am I wrong? Is there some kind of failsafe restart procedure?

Main question: Is there a fairly common mistake that people make doing a project like this might make, that I may have overlooked? Is there something that often gets broken during a job like this (inside dash or under hood - heater hoses were pretty difficult also).

I have not yet checked fuel pressure or ignition spark, but they are going to be first check. I did try pushing the schrader valve in the fuel runner port and there was a little pressure and gas squirt after every time I tried cranking, so I THINK the fuel pump is working.

Back in the day of non-computer-controlled carburetors, I could troubleshoot and fix almost anything, but these things are just too difficult. I feel lost.

Please advise?
 

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Discussion Starter #2
PM Update: For any wonderful person so inclined to weigh in on this, I have this update. It is definitely fuel supply related - there is no fuel pressure coming in to the fuel pressure regulator. I can only guess what "burping" I saw previously when pressing the schrader valve between start attempts was really a minimal pressure building up in the fuel rails due to residual fuel in the fuel rails. When I removed the fuel pressure regulator and observed the fuel inlet during a start attempt, there was no fuel spewing out.

Now, I am looking to see if problem is electrical or mechanical. I have checked the fuel shut-off relay in the trunk and it is reset OK. Also, fuses are OK. Haven't found the fuel pump relay yet.

Is there anything under the dash or in the steering column that I could have forgotten to reconnect that could disable the fuel pump? how about engine compartment around the heater hoses?
 

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Check your crankshaft position sensor.
 

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I was wondering about the CCRM. I did find it behind the air filter on tthe radiator support. Thanks for the link to a little insight on this module - I checked and 1996-1997 Tbirds use same module.

So, is there another relay outboard of this module before the fuel pump in the tank, or does the output of this module connect directly to the fuel pump? Exactly where does the inertia shutoff relay figure into this? I can't seem to find a decent wiring diagram for all this in any of the 3 service manuals I have. If I can trace the supply voltage to the fuel pump, I can figure this out...


What I am struggling with is whether something spontaneously failied during the 2 weeks that I had the battery disconnected (or maybe failed during battery reconnection) or did I break or forget to connect something back up when I took the dash out... ???
 

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I was wondering about the CCRM. I did find it behind the air filter on tthe radiator support. Thanks for the link to a little insight on this module - I checked and 1996-1997 Tbirds use same module.

So, is there another relay outboard of this module before the fuel pump in the tank, or does the output of this module connect directly to the fuel pump? Exactly where does the inertia shutoff relay figure into this? I can't seem to find a decent wiring diagram for all this in any of the 3 service manuals I have. If I can trace the supply voltage to the fuel pump, I can figure this out...


What I am struggling with is whether something spontaneously failied during the 2 weeks that I had the battery disconnected (or maybe failed during battery reconnection) or did I break or forget to connect something back up when I took the dash out... ???
Being a nearly 20 year old car, it is entirely possible that one sensor may just "go" after not being used awhile.

That said, I'd retrace my steps and double check all connections. Make sure the PCM is fully plugged in, etc.
 

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I put a couple of links in my previous post but they got blanked out - how do I overcome that. I'm thinking those links may be useful to someone else...
 

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I put a couple of links in my previous post but they got blanked out - how do I overcome that. I'm thinking those links may be useful to someone else...
I see the links.
 

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Update: I now know that I am not getting 12VDC to the fuel pump (i.e., the pump is not running at all). I have traced it to the CCRM - the output signal on pin 5 of the CCRM is nothing, no matter what the condition of the ignition key. I checked some of the input signals from the ECM/PCM to the CCRM - pin 12/24 is nothing (don't know what it should be), pin 11 is good 12VDC, pin 18 seems to float around 10-50 millivolts as if it were open. So I'm thinking maybe I knocked the PCM connector loose, but no, it seems to be plenty tight connected and all the cable connections that were undone during dash removal were correctly connected.

It got a little dark on me, I've got some more tracing to do.
I could sure use a complete schematic right now, haven't been able to find one.
 

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Update: I now know that I am not getting 12VDC to the fuel pump (i.e., the pump is not running at all). I have traced it to the CCRM - the output signal on pin 5 of the CCRM is nothing, no matter what the condition of the ignition key. I checked some of the input signals from the ECM/PCM to the CCRM - pin 12/24 is nothing (don't know what it should be), pin 11 is good 12VDC, pin 18 seems to float around 10-50 millivolts as if it were open. So I'm thinking maybe I knocked the PCM connector loose, but no, it seems to be plenty tight connected and all the cable connections that were undone during dash removal were correctly connected.

It got a little dark on me, I've got some more tracing to do.
I could sure use a complete schematic right now, haven't been able to find one.
Here is the MN-12 "bible". Full Ford service manual and the EVTM.
https://www.dropbox.com/sh/ghc1zorwt7dguuu/AACKOZkp8JKIQfXUSNV930yea?dl=0
 

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From the sticky in the Newbie Forum: http://forums.tccoa.com/5-newbie-forum/124074-common-acronymns.html

VMM = Vehicle Maintenance Monitor. Shows you if you have low fuel, low coolant, a door ajar, and for some if the firm ride is on but only for vehicles equipped with a VMM. Some VMM's have a button to turn the Traction Control off too.

I have the EVTM (Electrical and Vacuum Troubleshooting Manual) for the 95 and the wire colors shouldn't be much different.

The 13FL fuse in the Power Distribution Box sends power to the CCRM (aka IRCM) by way of the BK/Y wire. The CCRM sends 2 wires (PK/BK and LB/O) to the PCM but the PK/BK wire is the one that also goes to the Inertia Fuel Shutoff Switch in the trunk. Then it's a DG/Y wire from there to the fuel pump.
 

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Discussion Starter #14

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Thanks loads & loads & loads for tthe docs - tthis will help tremendously. I already had the volumn 2 of the factory service manual (I love also having in softcopy - easier to search), but none of the electrical diagrams, Thanks again.

Thanks again.
Happy to help. I tend to print off what I need before going out to the garage to work. Eventually I'll have the whole thing on hardcopy..
 

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Discussion Starter #16
I tend to print off what I need before going out to the garage to work.
I do the same. Thanks again.

BTW, I have attached a pic of the inside of my CCRM. I still have not determined for sure if it is bad, I like to make sure the input signals are OK before buying a >$100 part.
 

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Discussion Starter #17
The fuel pump relay is in the Constant Control Relay Module, (CCRM). This "box" is located in front of the air filter box.
Here is a link that is a good description of the CCRM.
http://forums.tccoa.com/17-audio-electronics/142854-ccrm-detail-1996-tbird-lx-4-6l.html
I was thinking that 96 and 97 CCRM boxes were same, but mine has one more relay in it besides the one shown in tthe "...ccrm-detail-1996-tbird..." document. Perhaps they are still the same, but one has an electronic switch while mine has a mechanical relay. (??)

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I am trying to understand the theory of operation to accurately troubleshoot this thing (I must be sure, I cannot afford to buy a $100 box just to test with). According to my understanding of the Operation Description in the factory service manual section 03, there are two different sources of +12V that are "wire-or'ed" to the fuel pump. One comes from pin 40 of the PCM and the other from pin 5 of the CCRM. I think PCM pin 40 provides +12V for about 1-sec when key is first put in RUN (for charging the injector rails) and CCRM pin 5 provides +12V during START and when engine is running. The CCRM pin 18 receives a ground signal from PCM pin 80 that energizes the FP relay in the CCRM. I think...

What I don't know is if there are any failsafes built in that shut things down if there's a short or some anomoly. Supposedly, the diagnostic procedures for this are located in a "Powertrain Control/Emissions Diagnosis Manual" that I don't have. Anybody know where I could get one or portions of it?
 

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The only safety cutoff I can think of is where if there is a short going to the PCM it won't turn on. You would know this was the case if your engine fan turns on the second you turn the key to ON. If your fan is functioning normally I would assume the PCM relay is fine but the fuel pump relay may not be fine. You could always try using a jumper wire to see if the fuel pump engages from the CCRM harness.
 

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Discussion Starter #19 (Edited)
This thing is driving me out of my cotton-picking mind. I am gradually becoming less suspicious of the CCRM and more suspicious of the PCM itself.

I can feel relays tripping when turning car ON (feels like multiple but can't tell which ones; vibrations travel throughout board).
I never see a ground being applied by the PCM to energize the FP relay in the CCRM during START; I never see the 1-second +12V pulse from tthe PCM to the fuel pump; at least, I think these are what I should expect.

... the PCM it won't turn on. You would know this was the case if your engine fan turns on the second you turn the key to ON. ...
The rad fan does come on instantly and runs at low speed when car is turned ON (I don't remember it ever doing that before, but I could be wrong). It does turn off when key turned off.

I tried hooking my scan tool up to the diagnostic port just to see if there might be anything that might tell something, and it would not communicate with the computer - it powered up, but returned a "failure to communicate" shortly after turning car on. hhhmmm...

... try using a jumper wire to see if the fuel pump engages from the CCRM harness. ...
I did try forcing +12V onto the CCRM FP relay output and the fuel pump did run;, next I'll try forcing the ground on the input to the CCRM FP relay to see if it really does energize - I am going to check a few more things as soon as threat of rain showers goes away.
 

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Discussion Starter #20
OK - I am reasonably certain that the PCM (or ECM) is defective or is not working (or not connected?).

I rechecked all the voltages going into the CCRM and they are good (HAT & HRS, good). I checked to make sure the CCRM Pwr Relay was working (+12V at CCRM pins 12 & 24, pwr to PCM and other relays in CCRM, good).

Still the FP signal from PCM pin 80 to FP Relay in CCRM never goes low (not even for 1 second when car first turned ON/RUN nor during START). BTW, I think I have a better understanding of how it should work and my previous understanding was in error - all fuel pump control is thru this input and the connection back to the PCM pin 40 is a FP monitor, not another FP enable.

I tested by manually connecting a ground to the FP Relay control input of the CCRM (pin 18, LB/O wire), and it worked: the fuel pump ran OK.

I checked spark (spark tester) and injector signals (noid light) and nothing/nada/zip/diddly squat during START (sure could be caused by other things, but what are chances ...).

I rechecked with my scantool and again it would not link/communicate with vehicle.

Sounds like PCM/ECM for sure. I have checked all fuses that go to PCM circuits - none blown.

Any other thoughts?
 
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