1998 GMC Jimmy Checkk Engine Code

I have a 1998 GMC Jimmy and have been getting some repetative check engine codes since August 21 (I own a code reader). The first encounter I got codes P0740 (Torque Converter Clutch Circuit Malfunction) and P1860 (Manufacturer Specific DTC). Vehicle acted like it could not downshift when first set of codes were received. After a few minutes vehicle returned to normal and shift just fine. Got the same codes on 8/22. Next encounter was 8/27 with the same set of codes. Then on 8/29 got the same codes but this time the instrument cluster seemed as though it lost power but vehicle kept running fine. Tried to turn off vehicle when in park but could not turn key far enough to remove. Turned on and off several times and then was able to shut off and remove key. On 9/4 got a couple new codes along with the same codes mentioned above. They were P0753 (Shift Solenoid A Circuit Electrical), P0758 (Shift Solenoid B Circuit Electrical), and P0758 (Shift Timing Solenoid Malfunction). Again vehicle seemed like it could not downshift. After a few minutes vehicle clicked back into normal mode and run and shifted fine. Since 9/4 I get sporadic check engine light with a mixture of th codes mentioned above every couple days. Vehicle seems to run fine but when light comes on it seems like it doesn;t want to downshift properly. I'm an elecitrcal engineer and this seems to me like an electrical problem.

Any help from anyone out there with similar experiences would be greatly appreciated and with what to do to fix problem. I know with previous experience when you bring a vehicle in intermittent electrical problems it is sometimes hard for techs to diagnois right away. I have been logging each check engine light experience on paper with the codes received and how the vehicle reacted.

Brian

Most likely cause of multible transmission electrical codes is a faulty ignition switch.
I have replaced many switches for that complaint.

Brain, I too have the exact same problem with my 1999 jimmy, I have been fighting with it for two months now and have been at a total loss. I pulled the error codes and had the following:
P0753 P0758 P0785 P1860 P0740... I figured err # P1860 TCC sensor must being triggering all the others to fail too. I replaced mine and the codes are back again. So I figured there is nothing wrong with the transmission sensors and started to look for some other cause. The truck shifts fine and I am assuming the codes are false triggering. I have seen the same problems with my dash and figured it to be a short / alternator / batt / charging issue. Never thinking it could be releated to the transmission sensors (I thought all the sensors would goof up not just transmission, i.e. o2/map/...). I saw a reply to you post about the ignition switch, I have heard this before but haven't tried it. Did you try it? did it solve it? any suggestions?

Thanks, CJ

I second merlin, look for a circuit failure in the ignition switch, not all that uncommon. But what a
great problem to solve the first time you see it, NOT!

Can anyone give me some insight on how to change the ignition switch, im having problems with no power at all in the vehicle and a stuck key. I released the key lock with the release button. Basically happneed when i went to start it, sounded fine and about 3 seconds after it shut down. All power shut off obviously the engine as well and the key wouldnt turn. I dont want to spend all kinds of money on something i can probably handle myself. thanks!!

I have a 2000 Jimmy and it is driving me nuts. No pun intended. Am getting the same error codes that you posted.(P0740,P0753.P0758,P1860). (A friend has a snapper code reader.) Also can't get the key out of the ignition, just sometimes like you stated. Also dash gauges would go off, no gas no speedometer. The lights come back on when I press the button to change gears on the gear handle. i.e. change from park to drive or reverse. Also the car seems to be stuck in second gear. Was going to take it to a transmission place, but will first change the ignition switch like you have suggested, it is a lot cheaper than a new transmission! Thanks, and wish me luck. Nowoeks1

replace the ignition switch wiring harness. This will take car of your problem. Cost about $100 for harness and takes a few hours to install. Really a pretty easy job. A faulty ignition switch will also cause you to not be able to take out you key (on occassion), cause the gauges to go out and come back on when button on shifter is pressed.

Thanks for your reply. Replaced ignition harness, got the car to start once. Now it cuts off after about 2 seconds. I think it has to do with the anti-theft, but not sure. Thanks for your reply. Still motionless. Ready to take to dealer.

OK I just bought a 97 Jimmy SLT. I love the truck however I have this exact same problem. I replaced the VSS yesterday in hopes to resolve the problem (I came to this conclusion from this forum) but it didn't work.

Has anyone replaced the ignition switch and it actually fixed the problem? If so how much did it cost? Is it something a backyard wrench can do?


HELP in Anoka, Minnesota...!!!!

^^Bump this one up^^

Changing the ignition switch resolved the error code problems.Had to take the car to a dealer to reprogram the ignition computer. The car thought it was getting stolen! Am on the road again.

I had the same problems with my wife’s Jimmy (i.e. loss of dash electronics and stuck in gear). My vehicle is covered by an extended third party warranty but every time it went into the shop it didn't act up. I purchased a code reader and drove around with it plugged in until it happened and low and behold a 502 code popped up and then cleared itself so I replaced the VSS, We are now going on 3 weeks with no problems (knock on wood) it was happening every day.

I have a 97 Jimmy and have been having some similar issues. Am getting the same error codes that you posted.(P0740,P0753.P0758,P1860). Also can't get the key out of the ignition, just sometimes like you stated. Haven't had any probs w/ dash gauges or anything but the car (http://www.automotiveforums.com/vbulletin/t135774.html#) seems to be stuck in second gear but will shift if I manually move the shifter into first. I've read these posts about changing the ignition switch, just wondering who has had success with this before I start buying parts.

I have a 97 Jimmy and have been having some similar issues. Am getting the same error codes that you posted.(P0740,P0753.P0758,P1860). Also can't get the key out of the ignition, just sometimes like you stated. Haven't had any probs w/ dash gauges or anything but the car (http://www.automotiveforums.com/vbulletin/t135774.html#) seems to be stuck in second gear but will shift if I manually move the shifter into first. I've read these posts about changing the ignition switch, just wondering who has had success with this before I start buying parts.I have replaced the ignition relay, which is in the steering column, and it corrected my issues. Part, which is a small wiring harness with the ignition relay, costs around $125

I have a 97 Jimmy and have been having some similar issues. Am getting the same error codes that you posted.(P0740,P0753.P0758,P1860). Also can't get the key out of the ignition, just sometimes like you stated. Haven't had any probs w/ dash gauges or anything but the car (http://www.automotiveforums.com/vbulletin/t135774.html#) seems to be stuck in second gear but will shift if I manually move the shifter into first. I've read these posts about changing the ignition switch, just wondering who has had success with this before I start buying parts.
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