computer replacement question

[nowan]

I just bought a 92 laredo 4L ho auto

the washer fluid low light was on but the jug was full.
I pulled the sensor and when it was plugged back in the computer blew
(heard it POP, and could smell the burnt cap)

so now I need another computer and there are no other 92s in the local wreckers - what other years are compatible??

any help or suggestions appreciated

[XJ Buzzard]

There was a brief thread on this about 2 weeks ago. I think 91-95 are the same just as long as the options are the same. I think the link below might work.

chris

http://www.naxja.org/forum/showthread.php?t=63445&highlight=1992+4.0L+PCM

[Lou]

The likelyhood that you did damage to the ECU by pluging in a sensor is extremely low.

You actually see a blown capacitor(or other part) on the ECU?

[jfiscus]

I have a 93 computer out of an XJ I just took the motor out of, make me an offer lower than the junkyard wants from you and let me know what shipping wil be like from Ohio. That darn light always stays on in my XJ and now the thing has started flashing all the time, and the bottle's 3/4 full. I'm just gonna remove the light; it's really simple to remove it.

[nowan]

Chris thanks, that was exactly what I was looking for.
My numbers are the same as Tazz posted.
I can go to the wreckers on Monday and get the 93


There was a brief thread on this about 2 weeks ago. I think 91-95 are the same just as long as the options are the same. I think the link below might work.

chris

http://www.naxja.org/forum/showthread.php?t=63445&highlight=1992+4.0L+PCM

@Lou - I was surprised too, didnt think that would be controlling the washer fluid sensor. I did hear the POP, and when I took it off and opened it, it smelled stronger. The conformal coating is discoloured around the one large Cap. (its 470microF I think) I will try to dig it out once I have a replacement. When it was plugged back in, no spark no fuel.

@jfiscus - thanks for the offer. If I can use 91 - 95 I should be able get one $40 locally, I'll let you know if I cant. If I have to use 92 only it will cost over $150 and take 2 weeks.

[Lou]

The conformal coating is discoloured around the one large Cap. (its 470microF I think)
:D

If it's the one next to the 3-terminal regulator you would be correct.

Although, the discolouration may have from the heat of the reg.

Best of luck with the $40 fix.

p.s.

I checked a '91 FSM, should be the same for '92 -- there is no connection to the ECU. The washer bottle level switch connects directly from radio fuse to the instrument cluster.

Just in case, check all the fuses in the PDC(next to the battery) -- especially the ignition fuse.

[nowan]

Its alive!!

took it too get the wiring checked, all OK. No apparent problems.
plugged in ECU from a 93 and it fired right up. Still dont know what caused the problem though, but for now its all good

[JeepSpeedRacer]

...I checked a '91 FSM, should be the same for '92 -- there is no connection to the ECU. The washer bottle level switch connects directly from radio fuse to the instrument cluster...

This is what I suspected too (I don't have my FSM in front of me). So, if the washer quantity wiring is NOT hooked to the PCM, why the popped cap? Is it possible that there is a shorted wire in the bundle adjacent to the washer wiring? If so, you'll toast your new PCM too.

[Lou]

This is what I suspected too (I don't have my FSM in front of me). So, if the washer quantity wiring is NOT hooked to the PCM, why the popped cap? Is it possible that there is a shorted wire in the bundle adjacent to the washer wiring? If so, you'll toast your new PCM too.Difficult to say.

A short is possible, but not likely. I've never been wrong before. :rolleyes:

Without getting into too much electro-bable, that type of cap pops from over-voltage, (or hi-freq noise)--It would have had to of been more than 25V. Also, when they pop, their little heads pop open--there should be a little mess. They are designed to do that.

[nowan]

I think I have solved why the short happened.

the battery had been replaced before we bought it, it is smaller than the original, but the original (larger) tie down was used. The positive was loose and kept touching the battery tie down, I can see marks on the tie down were it has arced.

The only reason I noticed this is that I finally did what I was supposed to do and DISCONNECTED THE NEGATVE TERMINAL FROM BATTERY. D'oh
Could have saved myself alot of time and money - guess its in the manual over and over for a reason.

for future reference here are the computer/ECU numbers I have found that work

56027 488 (my original)
56027 557 - I think anything starting 56027 will work
56028 297 - from a 93

thanks

[mikeny59]

What's the ballpark $$$ on a cpm, '98 for instance, oem

Thanks,

Mike