Fries anyone? Codes 543 and 634

[tripletdaddy]

In my enthusiasm to help someone out with their thread, I may have fried my EEC/PCM!?! I have a 95, 3.8L, 80k. I think I had shorted battery voltage through my ECT harness to the EEC/PCM in a momentary lapse of reason. I could smell something got hot inside and outside the car. I can't recall, as it was a week or more ago when this happened, but I think the car was running and stalled when I did my dumbness. Anyway, I finally got the courage to investigate the damage with a test drive and my ECM/ABS code reader. When driven, the check engine light would come on and off, but not much. The car ran like crap. Running rough and acting like it wanted to stall and sometimes would stall when stopped. The engine would run better at higher rpm, but was still not right. At idle, when it tried to keep from stalling, it would run rich, as I could see black smoke and smell gas from the exhaust. When starting at a stop and pushing hard on the gas, lots of black smoke could be seen.

I got the above codes. According to my Innova code reader manual, 543 is" fuel pump secondary circuit failure," Haynes says 543 is "fuel pump circuit open: battery to ECA." What do these mean and what can I do to make a repair? Haynes is of no help and doesn't mention a secondary fuel pump circuit. Innova says 634 is "manual lever position voltage higher or lower than expected." Is this the column gear shifter? What can I do to fix this? Is this the TRS voltage? Is there a way I can test my EEC/PCM? To confirm, it is located on the firewall right below the EEC and ABS test ports or is it inside behind the glovebox? What does it look like, as I think what I have seen by the datalink is the ICM, not the PCM so far?

Everyone's help will be greatly appreciated so that I can avoid too much tail chasing, blind part replacing and pointless investigating. Thanks!!!

[tartersauce]

Originally Posted by tripletdaddy

In my enthusiasm to help someone out with their thread, I may have fried my EEC/PCM!?! I have a 95, 3.8L, 80k. I think I had shorted battery voltage through my ECT harness to the EEC/PCM in a momentary lapse of reason. I could smell something got hot inside and outside the car. I can't recall, as it was a week or more ago when this happened, but I think the car was running and stalled when I did my dumbness. Anyway, I finally got the courage to investigate the damage with a test drive and my ECM/ABS code reader. When driven, the check engine light would come on and off, but not much. The car ran like crap. Running rough and acting like it wanted to stall and sometimes would stall when stopped. The engine would run better at higher rpm, but was still not right. At idle, when it tried to keep from stalling, it would run rich, as I could see black smoke and smell gas from the exhaust. When starting at a stop and pushing hard on the gas, lots of black smoke could be seen.

I got the above codes. According to my Innova code reader manual, 543 is" fuel pump secondary circuit failure," Haynes says 543 is "fuel pump circuit open: battery to ECA." What do these mean and what can I do to make a repair? Haynes is of no help and doesn't mention a secondary fuel pump circuit. Innova says 634 is "manual lever position voltage higher or lower than expected." Is this the column gear shifter? What can I do to fix this? Is this the TRS voltage? Is there a way I can test my EEC/PCM? To confirm, it is located on the firewall right below the EEC and ABS test ports or is it inside behind the glovebox? What does it look like, as I think what I have seen by the datalink is the ICM, not the PCM so far?

Everyone's help will be greatly appreciated so that I can avoid too much tail chasing, blind part replacing and pointless investigating. Thanks!!!

I think your Main Fuse Box has the FUSED diodes there, and it should protect your ECM. Look up your wiring for them, and see if they are there. If you smelled burnt, I dont think you killed your pcm but maybe something else.. Unless you were probing the ecm pcm itself..

[tripletdaddy]

Thanks tartersauce. I hope you're right!!! I'm going to look at it soon and will get back later today/tonight with results. I'm afraid though that I may as well been probing the the PCM directly as I was probing the wire for the engine coolant temperature sender, which goes directly to the PCM according to the wiring diagrams I have, including one from Ford. I hate it when grown men cry and it's me!?!

One thing I forgot to mention, I was suspicious of fuel pressure with the code, so I stuck my tire gauge on the fuel rail after koeo and while running. With one turn of the key, I got ~15psi, with multiple key turns ~20psi. While idling, 20 to 25 psi. I thought maybe when it was trying to stall the pressure would be lower, but it was no different when I tried to "catch" it with the tire gauge when it was stalling. I know that these pressures are too low, but prior to my short minded event, everything about the car was fine. I would expect that whatever I did also created the lower fuel pressure.

Once again, anyone with help would be greatly appreciated.

[tripletdaddy]

Tartersauce, I haven't been able to locate any diodes so far. There are only large and mini fuses in the main under hood power distribution box, likewise the IP box. You may be thinking of the diode that is in the main box for newer vehicles. My windstar has the diode there. Of what I could research, either the front O2 sensor is bad or I smoked the PCM. I haven't yet figured out a possible the cause for the 634, transmission range voltage too high or too low, other than assume the worst.
thanks

[shorod]

Ouch!

Does your Innova have a datastream mode? If so, what does it show for coolant temp? The coolant temp reading could cause the rich running. You certainly don't want to experiment too much as rich mixture = death to catalytic converters.

I wouldn't put a lot of weight on the fuel pressure readings using the tire pressure guage, unless you have a baseline reading using the same guage. You probably want to go ahead and pick up a fuel pressure guage. I'm not sure what might be different between a guage intended to read air pressure and one that's intended for liquid though.

Unfortunately, there are no diodes for any of the sensor inputs that I am aware of. The diodes tend to be on electromagnetic coil circuits such as for the A/C clutch, fuel pump, and some of the relays.

I'm getting a late start tonight, so unfortunately I can't go through my manual to dig out the diagnostics for the codes.

The PCM is located behind the glovebox on your '95.

-Rod

[tripletdaddy]

Thanks Rod for your input. Don't knock yourself out on this too much as I have the same FSM to research thanks to you, but I'm still getting used to it. So far I haven't really found much to test the PCM. What flow chart I've found on the 543 code leads me to a bad PCM. BOOO! The burnt smell was the strongest inside. I've dug my way into the dash and see a metal box buried above the blower box, which I assume is the PCM. Geez! You have to get to it from the engine side too and they made it no fun to get at it on both sides!?! Rrrrr!

My Innova is just your bare bones Ford EEC and ABS tester and code retriever and clearer for 81 to 95 Fords. So, no datastreaming. Will think about the influence of coolant temp on fuel, can I "trick" it to change fuel? Will investigate the fuel psi measurements some more. Does anyone know what the secondary fuel circuit is? Any chance of fixing this one circuit on the pcm, when the rest seems to work? I may be able to answer that question when I get it out and open it. Where can I get a PCM cheap but usable besides a junkyard and ebay? I've noticed that retail and private sales don't know the difference between a PCM and a CCRM!?! Starting with Auto Zone and listers on ebay!?!

[tripletdaddy]

I've decided to continue this thread in a new direction at the following thread link. I also address some suggestions and questions from here at this new thread Thanks.

http://www.automotiveforums.com/vbul...d.php?t=897738