wb22rules

My 93 which has never shown a CEL suddenly out of the blue on a start yesterday morning will barely run. This truck has had real light duty for the last decade basically only running 10 miles to the dump with trash bags weekly and a friend of mine using it weekly to go to the store and see his doctor once in a while. Recently I have had the opportunity to get on some nice hardwood 10 miles away and have been hauling green wood (about 20 loads) back to the house to replenish the firewood for next winter and beyond. The truck has been handling this duty like a champ, running strong and smooth with FULL loads.

Due to that information I think what has failed must be electrical as it was fine as wine, then overnight it is stumbling all over itself barely running until you give it throttle, but then it is still rough. It it was the fuel filter I would have noticed an issue with full loads recently, the pumps both power up normally and switching tanks has no effect on the problem, so I do not suspect fuel pressure or supply as what changed overnight.

I have checked the battery and alternator, both are performing normally. I have 12.8 volts before startup, voltage at the battery rises to 13.7-14 volts when running. Truck remains running when battery is disconnected while running, different battery also gets same results. I have checked the codes and I have about 18 different ones. All of the codes but one refer to a circuit failure or a sensor returning a lower than expected voltage, the one which stands out is code 513. This code in my alldata account is described as such "PCM Int Voltage Failure KOEO". I am afraid that means something has failed in the trucks computer which is preventing all of these other control circuits from getting any, or sufficient, voltage to operate. In the factory service chart that code has only 1 action to perform, Replace PCM. I am going to remove the PCM and attempt to investigate it. My question to the knowledge base here is, has anyone here had any luck replecing the ICs in the computer to repair it? The reason I ask is I am currently unemployed and cannot spend a dime unless I absolutely have to. I have found a PCM online at Auto Parts Warehouse for $101.00, but if I can replace the ICs for 10 dollars I would rather do that at the moment.

Thanks in advance

wb

wb22rules

Well after inspecting the PCM, none of the ICs or transistors are mounted in sockets, so it does not look like replacing any ICs at home will be easy or worth the time.

Has anyone had an issue where a sensor or component has failed and caused the PCM to fail?
If so what sensor or component would need to be verified before I put the replacement PCM in the truck, I certainly dont want to buy one only to watch it get "eaten" by something else.

wb22rules

After looking closely at the possible Cardone PCMs at the Auto Parts Warehouse site I finally saw the difference in all the PCMs with the different prices (9 of them). They referred to a four digit code and whether the vehicle was auto or manual, of course mine would have to be the most expensive one at $211, code F3TF and an automatic transmission.

Off to search for a cheaper one......

Edit - I thought Advance has the one I need for $200+ with a $40 core. But the one they have that matches the id sticker on mine says it is for a Manual transmission, and I have an auto??

tvand13

Someone much more experienced than me will have to confirm this, but is is possible it could be something like a ground to the computer?

wb22rules

It is possible the PCM may not be bad I would imagine, I have been searching my alldata account for a procedure or way to verify the PCM has failed other than the code 513 that was reported.
On some of the other codes I followed the troubleshooting procedure back to the point where I am instructed to install a breakout box to verify PCM failure, but I do not have one of those atm.

The connections and connectors are fine as I inspected them as I removed the PCM and also checked the large harness connectors at the firewall.
Since I do not have a breakout box, I cannot measure PCM pins while it is installed in the vehicle but I may be able to use the wiring harness info to find a way to check the same signal further down the wire/s. I was unable to find the way to check the PCM reference voltage transistors with it outside the truck with my multimeter using the Ohm or diode check function, but I think I should be able to do so, I just am not sure what pins and what values to check for in order to verify that transistor/s have opened up.

wb22rules

For reference here are the codes that were retrieved earlier.
I removed the battery last night and left the cab light switch on to clear codes that may be old/unrelated, even though this is the first time the check engine light has come on since I bought this truck new.

I restarted the truck and let it run for about a minute idling and revving up to 1500 or so, then installed the jumper and read these codes below.

112- IAT sensor less than minimum voltage
117- ECT sensor less than minimum voltage
122- TP sensor less than minimum voltage
126- MAP/BARO higher or lower than expected
327- EGR below minimum voltage
513- Int Voltage failure KOEO
552- Secondary Air Injection Bypass circuit failure KOEO
556- Fuel Pump relay primary circuit failure
558- EGR vacuum regulator circuit failure
621- Shift Solenoid 1 circuit failure KOEO
622- Shift Solenoid 2 circuit failure KOEO
624- Electronic Pressure control circuit failure
626- Coast Clutch Solenoid circuit failure
629- Torque Converter Clutch solenoid circuit failure
631- Transmission Control Indicator lamp circuit failure KOEO
638- Transmission Oil Temperature sensor circuit below minimum voltage
654- Manual Lever Position sensor indicating not in nuetral during self test

wb22rules

I just cleaned up the two grounds that show being used by the PCM, they seemed in good shape.
I hate to buy a part just on a code without confirming the part is bad another way, especially parts that cost more $40.00, but usually there is a procedure to follow in the factory service manual first, that code 513 just says replace PCM. I am going to keep trying to check to see if there isn't a failed relay or solenoid loading down that voltage and causing all of these issues, maybe also tricking the PCM into thinking it has an internal failure. I think I am going to have to find a way to borrow or buy a breakout box for the 60 pin Ford EEC IV PCM though

wb22rules

To reduce confusion please post to the thread in the pre 97 f150 forum

https://www.f150forum.com/f10/anybod...d-pcms-206050/

and not this one, I posted this here in error.