Need your help. '99 tahoe not shifting gears


Old 11-10-04, 03:20 PM
Thread Starter
Join Date: Jul 2004
Location: Fruitland Park, Fl
Posts: 20
Need your help. '99 tahoe not shifting gears

I have posted this once before, but I feel like I may be ripped off if it's not correctly diagnosed. What happens is an intermittent problem. Sometimes the tahoe will not shift gears, as if stuck in a higher gear. Other times it shifts fine with no noticeable problems. Although the service engine soon light is on most of the time. It happens all the time when the tach, speedometer and gear indicator light quits working. They are intermittent as well. So far, one mech. said that it may be a short and another seems to think its the transmission solenoid, although he wouldn't guarantee that would fix the problem. The solenoid came up after he ran a diagnostic on it. I try to fix most of my auto problems but this one is beyond me.
Has anyone seen this before. I would be very grateful for any feedback.

Thank you very much, Byron
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Old 11-10-04, 10:09 PM
Join Date: Feb 2004
Location: So Cal
Posts: 248
I don't know if this will apply to your '99, but I recently came across a shift problem on a '97 Tahoe. 3-4 shift solenoid did not work. Turns out an internal ground in the PCM was bad and GM has a known fix for it by installing an external redundant ground. Costs about $160.00. You may want to check with your local GM dealer on this. It's a fairly easy diagnosis - about one hour labor.


Old 11-11-04, 05:13 AM
Join Date: Jan 2002
Location: New York
Posts: 49
A friend had a similar problem, it was an ignition switch problem. I believe it is a common problem.
Old 11-11-04, 04:26 PM
Join Date: Apr 2002
Location: Pittsburgh,Pa
Posts: 2,417
Without diagnosing it I would say ignition switch.When the trans loses any inputs it defaults to 3rd gear operation.If the service engine soon light is on please get it checked and repaired the problem may be connected.
Old 11-18-04, 04:04 PM
Thread Starter
Join Date: Jul 2004
Location: Fruitland Park, Fl
Posts: 20
you guys were right. turns out it was the ignition switch after all. it only cost $295 to have it replaced. I would have gladly paid more. I'm just glad it is fixed. I printed our thread and left it for him to ponder. that day he ordered the switch for it and installed it the next.
Thanks again for your input.


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