3 Blown Pcm In One Month!!!!!!

[saulnieto]

I Am Desperate For Help I Bougth This 95 Talon Non Turbo, Replaced The Engine, And Ever Since It Can Not Run For More Than A Week Without Blowing The Pcm, The Mechanic Says That It Is The Engine Wiring Harness Or The Cam Gears But I Do Think He Is Just Guessing, I Am Gonna Be Broke Buying Pcm's If Nobody Figures What Is Wrong With This Car!!


Help Please

 

[luv2rallye]

Try measuring the voltage at the battery with engine running different rpm's. If over 15V your alternator is putting out too high a voltage and burning it out.

 

[sillycon]

What part of the PCM/ECM/ECU is burning out? I'd start by analyzing the dead computer, then work backwards on the blown circuit to find the problem.

 

[akdsmer]

A shorted solenoid in the EFI circuit will cause an extremely high amount of current to flow into the PCM. The PCM is designed to handle up to 1.1Amps on all loads except for the injectors and the coils. In the DSM's case, the coils are not directly connected to the PCM so this is likely not a problem. Failure to test these circuits for shorts before sticking in another PCM could result in another PCM failure.....

I would disconnect the battery, pull the PCM harness and do an ohms test between pin#13 Black/red and the following pins on the WIRING side of the harness (ie not the pcm pins):

1,2,14 and 15: these are the injectors (around 10-15 ohms)

3,11,9 and 6: these are the solenoids. (around 20-35 ohms)

54 and 60: these are the O2 heaters. (around 5-20 ohms)

4,5,17 and 18: these are IAC motor windings. (around 30-40 ohms)

Also check the resistance of the MFI relay (near the PCM). The blu/grn and red/blk wires, and also the reading between the blk/wht and wht/red wires. (these are also likely to be around 20-35 ohms).

I have the values written down somewhere, but I usually use a low amp probe to do a better dynamic test. These readings I listed should be close (others can correct me if they wish)
Record the ohm readings. We (you) are looking for reading which are extremely low. Post back up with the results.

 

[saulnieto]

Well, the mechanic so far traced the fault to a "resistor" inside the computer, I just ordered another one because this one was under warranty, I told him to inspect all te previous mentioned things once I get the new pcm before installin it to prevent it from happening again, the way this computer failed was like the car was running and all of a
sudden it would just die, and it would crank and everything but no start. the last time before I took it to the mechanic, I just moved it to the front of the house to wash it and after this it just would not work the mechanic replaced the computer and after starting the car with the new one it did not even run for more than 10 minutes and it died.


I appreciate all input on this issue and I will keep you posted on what it is that is causing this problem once it is fixed.