Getting strange results from KOEO test, PLEASE HELP!!!

[cgexploder]

So, recently the CEL came on in my '92 EB explorer. So I went through the procedure described in the haynes repair manual. First I just hooked up the test pin and read the codes off the CEL. The results were 22 / 22/ 1 / 22 / 66 / 22 / 66. If MrShorty is reading this, yes I know I should be getting 3 digit codes but I am not. I'm not misreading this I have done it several times. I even hooked up the old voltmeter and tried it again to see if I got a different result with that method and I didn't. So can anybody tell me what this means. I read in the manual that 22 is "Manifold Absolute/Baro Pressure Sensor out of range (low)" unfortunately as far as I have been able to determine my car does not have a MAP. Has anybody else had a similar problem. Any help is appreciated, but please don't tell me to search the forum unless you have a specific thread, because I have been haunting this forum for a week and have yet to find anybody that had this problem or found a solution to it.

cgexploder

 

[MrShorty]

Has the PCM possibly been replaced at some point? If so was it replaced with a '91 PCM?

'91's output 2 digit codes, so I'm wondering if you have a '91 spec PCM. If memory serves, '91'd did have a BARO sensor. So, if someone has put a '91 PCM into your '92, a 2 digit BARO code would be expected. It would probably be nice to confirm that suspicion if you can.

That doesn't explain, the CM 66 MAF code, though. I would guess that your CEL is mostly related to the MAF error. 1st thing I'd probably do -- clear CM, test drive, and see if the CM 66 stays away or comes back. I'd probably clean the MAF (instructions are in the useful threads forum, I believe) to make sure it isn't a dirty MAF causing the code. If the CM 66 doesn't come back immediately, keep driving it until the CEL comes back on, and then see if the CM 66 is the code, or if it comes up with something else.

 

[cgexploder]

Thanks for the response. I kind of suspected something like that but I'm not sure. I bought the car in 2002 so it could have been replaced before I bought it, but would a '91 PCM even work with a '92 engine and sensors? I've already cleaned the MAF, as I've had problems with it in the past(several years ago). I'll try clearing the codes and see what I get.

cgexploder

 

[MrShorty]

but would a '91 PCM even work with a '92 engine and sensors?

'91 and '92 use the exact same long block, and the engine managements systems are very similar (BARO sensor is the only difference I can think of off the top of my head). So I wouldn't be at all surprised to see a '91 PCM work in a '92 truck.

 

[cgexploder]

Hmmm, interesting, but I wonder why I haven't seen this error code before now?

I went ahead and cleared the error history, and pulled the codes again and got 22 / 22 / 1 / 1 / 1 then I did it again and got 22 / 22 / 1 / 22 / 22. I think the 66 code that showed up earlier came from me unplugging the MAF to check if it was the MAF instead of the MAP. But it idled rough when I did that and obviously ran differently than when it was plugged in so I figured that was just a phantom (or at least not a total failure of the MAF).

So, as far as confirming if I have a '91 PCM is there a way to tell the difference physically between a '91 and a '92? And where is the PCM located anyways?

 

[MrShorty]

Hmmm, interesting, but I wonder why I haven't seen this error code before now?

Not all errors cause the CEL to come on or come on consistently. I don't know how consistently BARO faults cause the CEL to come on.

So, as far as confirming if I have a '91 PCM is there a way to tell the difference physically between a '91 and a '92? And where is the PCM located anyways?

PCM is located in front of the passenger door, below the glove box, behind the kick panel. I doubt there are any physical differences that you can readily see between a '91 and a '92 PCM. Part number would almost certainly be different, though. I expect that would be the easiest way to know what kind of computer you have.