Update: out of my conscious thought regarding the mustang and T-birds' pcm/alternator issues associated with the P0340 code, I just bought an updated pcm from a site that addresses the issues stated. When it gets here, I'll install it. If the the code clears, I will return the alternator I bought from autozone and will effectively swapped one $100+ dollar piece for another lol. Didn't feel like cutting into the factory wire when it looks intact from an optical point of view. P.s.. that electrical tape that's wrapped around the wire is for the shielding wire that got loose. Someone did this suspect job and wanted to see what was under it lol.

1997 Ford Thunderbird ECM | Engine Computer PCM ECU Programmed & Updated

Engine Computer fitting all 1997 Ford Thunderbird models. Compatibility will vary for these units, please review the list below to ensure it will fit your vehicle.

www.fs1inc.com

 

I put to safety pins in the connector to pick up ohms but I'm not getting anything. Not sure if it's a break in the wire or I'm not digging down far enough. Is it a constant 12 or 9v for the wire? If it's truly an open circuit like p0340 states, it's a easy fix with a new wire connector or finding a break( if it's easy to get to)

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... Ok, so the Camshaft Position Sensor. The Gray / Red stripe wire is a 5 volt reference signal voltage supplied by the PCM - this same wire is what supplies voltage to the O2 sensors, engine coolant temp, and a few other things.

You should get 5 volts if you are using your volt meter positive lead on the Gray / Red wire, and negative lead to a good know ground ( you can check the shielding wire for good ground also ) ...

You wont get any ohms reading if you are checking the harness end to the EEC. You would check the camshaft sensor end for resistance using the leads on the volt meter ( ohms setting .. Not sure what the factory spec is ) .. If you are getting an OL ( over limit ) .. It would indicate an open circuit ( bad sensor ) .. Alternately, you would use Ohms to check the wire itself .. From the EEC connector, to the Cam sensor connector ( both unplugged, you are only checking the wiring in between for continuity ) .. It may be necessary to unplug all components sharing the Gray / red wire to get an accurate reading .. For simplicity, lets assume you already verified 5 volts at the cam connector end - we can assume it is good. The wire that returns the signal from the cam sensor is the one you need to check .. If this wire has a break or something, it will bring up the "open circuit" diagnostics trouble code you are looking at.

Checking the cam sensor itself .. Well, that steps up into the Graphing Digital Volt Meter / Oscilloscope type of waveform diagnostics. You would read the sin wave for frequency and amplitude at the cam sensor and at the EEC to determine what is being read by the EEC. Your standard volt meter will "average" the voltage out .. It will only give you a solid average number instead of an "on / off" type of duty cycle.

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🤔

... Ok, so the Camshaft Position Sensor. The Gray / Red stripe wire is a 5 volt reference signal voltage supplied by the PCM - this same wire is what supplies voltage to the O2 sensors, engine coolant temp, and a few other things.

You should get 5 volts if you are using your volt meter positive lead on the Gray / Red wire, and negative lead to a good know ground ( you can check the shielding wire for good ground also ) ...

You wont get any ohms reading if you are checking the harness end to the EEC. You would check the camshaft sensor end for resistance using the leads on the volt meter ( ohms setting .. Not sure what the factory spec is ) .. If you are getting an OL ( over limit ) .. It would indicate an open circuit ( bad sensor ) .. Alternately, you would use Ohms to check the wire itself .. From the EEC connector, to the Cam sensor connector ( both unplugged, you are only checking the wiring in between for continuity ) .. It may be necessary to unplug all components sharing the Gray / red wire to get an accurate reading .. For simplicity, lets assume you already verified 5 volts at the cam connector end - we can assume it is good. The wire that returns the signal from the cam sensor is the one you need to check .. If this wire has a break or something, it will bring up the "open circuit" diagnostics trouble code you are looking at.

Checking the cam sensor itself .. Well, that steps up into the Graphing Digital Volt Meter / Oscilloscope type of waveform diagnostics. You would read the sin wave for frequency and amplitude at the cam sensor and at the EEC to determine what is being read by the EEC. Your standard volt meter will "average" the voltage out .. It will only give you a solid average number instead of an "on / off" type of duty cycle.

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Thanks for the tips. I was getting annoyed that the clips I had would not pick up voltage for my voltmeter. Is it possible that the PCM has faulted/ shorted out to where it's not sending the 5volt signal to the connector?

 

Good writeup, Dan.

The sensor itself is a coil of wire next to a magnet, much like a guitar pickup. Instead of a string, it's reacting to the 'knob' on the drivers' side camshaft sprocket, one pulse each time it comes around. As Dan said, You need an oscilloscope to see it; a meter wont read anything except the dc bias.

 

Update: the volts on the output wire I 0.13VDC while no current being detected while in series. I read if it's noticeable current going through the wire it's most likely a faulty wire. In the little to no current situation it might be the pcm.