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testing 85 CJ computer?

707 views 8 replies 3 participants last post by  Jaffer 
G
#1 ·
I'm pretty sure my computer is dead on my 85 CJ but is there any way to test the circuitry on it?

 
#2 ·
It does have diagnostic hook-ups over by the battery i believe. It won't be easy finding someone with an adapter to get any info out though. Does it start? run? What's up with it?

Scott...

My Rides
1979 CJ-7: 304, 3spd, much is my rebuild
1983 CJ-7: 258, 5spd, for Peru Excursion
1989 XJ: has seen every state except Hawaii

In search of lost paths and distant locations...
 
G
#3 ·
The diagnostic hookups supposedly only give voltage readings. The Jeep is running but has no power. I have tested the coolant temp switch, thermal temp switch, stepper motor, wiring going to the computer, O2 sensor etc. and everything is checking out OK so far. The carb is one year old, the vaccum lines are all routed correctly and tight and the timing is correct. I'm pretty sure it's the computer but still not confident. Who knows, it maybe some stupid ground wire or something. The stepper motor does not run at all, I only know it works because I bench tested it. There is power going to the computer and stepper motor but nothing is happening. I was kind of hoping there was a way to test whether the circuitry in the computer is bad or not. Thanks

 
#4 ·
The voltage to the motor should be flutuating. If it's not, the means the computer's not commanding the motor to move. Either it's in open loop (because a sensor's not happy) or fried.
If all of the sensors are working properly, and the engine's at the proper temp, there's a good chance it's fried.

-Derek Schwab
'97 Sidekick Sport
'83 CJ-7
 
#6 ·
i agree with cj7350, but with the proper carb switch and necessary changes. The stepper motor should change the fuel mixtures for you, if your sure it works and there isn't any voltage from the computer, it just might be the computer. i hate to condemn it, does any sensor get reference voltage from the computer?

Scott...

My Rides
1979 CJ-7: 304, 3spd, much is my rebuild
1983 CJ-7: 258, 5spd, for Peru Excursion
1989 XJ: has seen every state except Hawaii

In search of lost paths and distant locations...
 
G
#7 ·
I don't know much about computers. But if you need one, I have one that I am getting rid of from my 82 CJ-7 (swapping V8). It is listed in the classifieds here for $20. Might be easier to install it rather than see if yours is bad. If you are interested let me know

Take Care

Shawn

82 CJ-7, dead 258, auto, 33's, 4.56 gears, detroit locker (rear) true trac (front)
 
G
#8 ·
True story, CJ-7 was getting no spark. I swapped out every component till the problem pointed just to the computer. Damn! Nothing to lose, I drowned the sucker with that "tuner/contact cleaner" in a spray can. I let it dry 15 minutes and whoopee!!, it fired right up. You might try that, worked for me.
Jim R
Reno, NV

Reno, NV 89434 home ph 775-356-5381
 
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