I have a 1998 chevy silverado automatic that has a shifting problem, when my rpm,mph gauges, and shift indicator light are not working my transmission gets stuck in 4th gear. This doesnt happen all the time, when they do work it shifts as usual and works really well. any suggestions?
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others will chime in but to me sounds like a for sure electrical issue. your saying when your speedo and tach and shift selector dont work... it wont shift out of 4th? first off, explain the scenario. are you driving and goin such and such speed, as it shifts into 4th, then your gauges blank out, and you cant get out of 4th?
1998 chevrolet silverado ext. cab
me in the driver seat
Thanks for replying, here is what happens: when i get ready to start the truck my indicator light is on, but when i start it and it is running the light goes off. When the light goes off, I know it will be starting in 4th gear. When the light stays on, it will start in 1st and switch gears normally. Yes, it sometimes the light will turn off after I've started, dropping me into 4th. Essentially, everytime the light turns off, I go to 4th. My check engine light is on and so is my check gauges light.
i have similar problems with my 98 chev,intermittently happened a month ago but now more often.i can start truck and it will work but a couple minutes down the road it will downshift to third and stay there.sometimes it will be stuck right from start up in the morning.some days it will be fine right from start up in morming for the ride to work and in afternoon it will be fine or not work.there is no absolute pattern here.same problems with indicator light going out,tach not working and speedo not working.
The culprit is the power circuit to the shift solenoids, circuit 1020(Suburban, will be different on a Silverado). There should be 12+ volts present at fuse 20 on the IP fuse box with the key at run. If not, the ignition switch needs to be replaced. If so, the 1020 circuit needs to be traced to the transmission. The circuits I am referring to are from a 1999 suburban with the same issues. I also had trouble codes P0740, P0753, P0758, P0785 and P1860. Also the tach and speedo did not work and it defaulted to 3rd gear with the 4L60E Tranny. The circuit numbers will be different, but the problem sounds the same. I hope this info helps. I attached the wiring diagram of the suburban that I have that had these issues. My particular problem was a short on the circuit. There were 12 volts present with fuse removed, but with the fuse in place there was only about a volt... indicating a short. Why the fuse did not blow is unclear. If I can find the TSB I will post it, too.
Here's an update, i should have posted awhile ago,it was the ignition switch,a little black box connected to the tumbler.Picked one up from the wrecker and had to cut all the wires and attatch the new/used wiring harness with the little black box attatched.i broke open the old one to see what the problem was afterwards and there was some steel/gold mesh contacts "very tiny" that looked almost completely burnt/blackened in the center of the contacts.over 250,000 kms on truck so i guess it was time.hope this helps someone out.
Read my last couple posts dale, it took a bit to figure out,cost $150.00 for a column from the wrecker with the ignition and all the wiring attatched,had to cut all the wires and take the ignition switch off with it and re-attatch them all but that is what fixed it for me.
Sorry it took so long to reply... I found the reason the shift solenoids were not getting power was because of the ignition switch. A quick way to test is to firmly, but gently, tap the area around the key with the butt of a screwdriver. You should see your Tachometer, etc. restore to normal. This continued to happen until I replaced it. I would say that I am 99.9% positive that is your problem.