Speedometer Question - 1991 Z28
08-31-2010, 06:24 AM
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Speedometer Question - 1991 Z28
Hi..hope I am posting in the right spot. I have a 91 Z28..completely stock and original. Lately the speedometer/odeometer/trip odeometer occasionally stops working. Then if you turn off car, restart sometimes it will work for awhile and then stop again. Sometimes the speedometer needle just bounces around. I read that if it was the VSS the cruise wouldnt work well that works just fine. Other than the VSS (and is that the right way to tell if working by using the cruise control) is it the gauge cluster that went bad most likely? Can those be fixed or do you have to replace?
Thanks for you thoughts/help in advance. Dan
Thanks for you thoughts/help in advance. Dan
09-01-2010, 04:06 PM
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Car: LOWERED ♦ CRIMSON METALFLAKE
Engine: ► 400 KUBES ◄
Transmission: 765R4
Axle/Gears: EATON POSI 4.56
Speed Reading
Monitor the speedometer signal with an audio amplifier to make sure it’s getting a steady signal.
Connect the amp’s input to pin 8
(gray wire) going to the dash connector on the right.
Ground to ground, the signal wire to the inner wire of the audio amplifier wire.
The next time the speedometer fails note if the signal stopped.
If it stopped, the problem is the ECM or wiring going to it.
If the signal was present the problem is the speedometer, or a bad connection in the dash.
◙◙◙◙◙◙◙◙◙◙◙◙◙◙◙
Happy Racing!
◙◙◙◙◙◙◙◙◙◙◙◙◙◙◙
My Brakes Don’t Work AT ALL When The Car Is In The Air
.
Connect the amp’s input to pin 8
(gray wire) going to the dash connector on the right.
Ground to ground, the signal wire to the inner wire of the audio amplifier wire.
The next time the speedometer fails note if the signal stopped.
If it stopped, the problem is the ECM or wiring going to it.
If the signal was present the problem is the speedometer, or a bad connection in the dash.
◙◙◙◙◙◙◙◙◙◙◙◙◙◙◙
Happy Racing!
◙◙◙◙◙◙◙◙◙◙◙◙◙◙◙
My Brakes Don’t Work AT ALL When The Car Is In The Air
.
09-18-2010, 11:17 AM
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Car: 1991 Z28 Conv.
Engine: 5.0 V8
Re: Speedometer Question - 1991 Z28
Unfortunately I don't have the answer to your question, but I thought I would share my experience. I too have a 1991 Z28 all original 30k miles. Two years ago my speedometer and odometer stopped working. I haven't driven it since. I did replace the VSS and I was disapointed to find that this was not my problem. I haven't tried anything else, too afraid that I'll mess things up more. Haven't found any real useful information either.
09-18-2010, 01:11 PM
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Car: 91 Z28 24th Anniversary
Engine: L98
Transmission: Auto
Axle/Gears: Posi 3.23
Re: Speedometer Question - 1991 Z28
If you have a scanner or know someone who has a scanner, you can check vehicle speed to see if the VSS is working properly when the speedometer is acting up. Actually, your check engine light should come on and a speed sensor code 23(i think) for the car being in gear and a high RPM with no MPH if it's the speed sensor. You may even be able to go to a shop and they may hook up the scanner and test drive for a nominal charge. That would be the first easy thing with no disassembly.
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