OMG... I hate those headlights.

 

Hi Guys and Gals,

So I ended up buying this Jimmy, and I really like it. Took it wheeling and it did very well. Wouldn't you know it, as soon as I finished it threw a check engine light. Well, "Service Engine Soon" rather. I stuck a paperclip in ports A and B of the OBD like I read online and tried to count the flashing, but the flashing was very haphazard. I couldn't really make out a pattern.

What I'm wondering is if anyone has an OBD reader that would work with an 89 that they recommend? I'm assuming it's OBD1. The code could be for anything, but if you guys have one thing show up more than others after 4x4ing I'd like to know that as well and I could check that out on my vehicle.

Thanks a lot!

 

I have an Auto X-Ray for my 89. Useless piece of C***. I think most auto stores like Autozone will now read your trouble codes for free. If you do decide to learn how to read the codes using the paper clip trick, it should give you code 12 first (which is normal even if there isn't a check engine light). After code 12 there should be a 'long' pause followed by quick blinks then a short pause, then a long pause followed by code 12 again. For example, 1 blink - short pause - 2 blinks - long pause - 3 blinks - short pause - 6 blinks - long pause - 1 blink - short pause - 2 blinks. That would be codes 12, 36, 12.

 

I recommend against taking the 'most probable cause' approach. You'll just end up frustrated by the time and money you waste on your new toy. Can you give us any more clues, like when did you notice the light. Was it during an extreme elevation change, temp change, stop/go traffic. It could have been a one time problem. The code will go away after 50 starts if it isn't a persistent problem, or you can clear the code by disconnecting the battery for 10 mins and see if you get the check engine light again, in which case you should diagnose it in a methodical manor. If you don't fix the problem and the light stays on then the engine might get bad fuel economy and worst case it will run in 'limp mode' and run poorly. Like I mentioned before, have an auto store do a free scan on it.

 

Thanks for the input Rampage. I actually have an OBD2 reader which I assumed was not compatible with a pre 1994 vehicle, but from what I have read online today, perhaps it is. I will try when I get home later today with my scanner and see if I can read it. Otherwise I will try the paperclip again now that I know the 12 will show up twice. I think that is what was screwing me up.

Thanks again.

 

Yeah, I forgot, it's ODB II so it should work, but look up your scanner online from the manufacturer of your scanner to see if it's for an 89. And thank you for correctly spelling my misspelled username. That's what I get for registering after having a few.

 

Alright... I got the error code via the paperclip (my OBD II didn't fit). Code 42 - The EST signal did not change when the ECM applied bypass voltage to the ignition module.

Also, the Jimmy won't start anymore. It tries, but just can't do it. So this makes sense that it refers to the ignition module. I found this diagram online - Diagnostic Codes

Any suggestions?

And that's funny about your username... I actually misread it. haha.

 

Yes, follow the instructions in the diagnostics chart.

Actually, I have no useful information for you on how to diagnose the problem since I've never had this code thrown before. But I do have a sneaking suspicion that it may cost some $$. I'll try to do some research if I get a chance. Sounds like it should be easy enough to troubleshoot if you have a multimeter and know how to use it. It might be useful to start a new thread (like 'Help troubleshooting code 42') so it'll catch more people's attention.