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View Full Version : Speedometer drops to zero



rusty6k
04-10-2008, 11:59 PM
Our car is having quite an unusual problem; I'll start with some basics:
1988 Pontiac 6000 Base Model
Iron Duke 2.5L
Automatic Transmission

Occasionally, around 50-60km/h, the speedometer will drop to zero. It will stay at zero until we either speed up or slow down. The problem is intermittent, and usually unaccompanied by any performance problems, though my girlfriend said it sounded like the engine was overworked the last time it happened.

The phenomenon is unaccompanied by a check engine light, and doesn't happen every time.

Anyone experience something like this/any ideas?

CieraSL92
04-11-2008, 12:28 AM
Somebody will have some ideas about this. Do you know if this speedometer is operated by a cable, or a Vehicle speed sensor?

86euro
04-11-2008, 01:38 AM
My first thought would be to check the wires going to the VSS on the tranny.

Techfizzle
04-11-2008, 01:46 AM
huh? unless its a digidash tthey have cables id check the cable.

MorMan88celeb
04-11-2008, 01:46 AM
Just check, or have a mechanic check your wires. The tachometer on my old Bonneville used to peg all the way over to the right at random times. There ended up being a short in the wire that feed into the distributor. I never botherd to fix it though..lol

86euro
04-11-2008, 01:57 AM
huh? unless its a digidash tthey have cables id check the cable.

Celebrity and 6000 both got electric speedo starting in '87. Actually, now that I think about it, 6000 may have before that.

Techfizzle
04-11-2008, 02:15 AM
then it would be safe to say a dirty or bad vss

85_Ciera_Rebuild
04-11-2008, 02:44 AM
then it would be safe to say a dirty or bad vss

It would be safe to say from the speed-o to vss, there is a problem.

Could be a wiring issue, could be a speed-o head issue, could be vss, etc.


I drive a vehicle with electronic speed-o that requires about a ten mile drive to "start it up," and any speed below 30 mph, it will not register. Another vehicle I drive has a digital dash, and many times, it takes about 15-30 minutes of drive time to "wake-up" the speed reading display.

Oh, I haven't fix either problem, I use the Tach to figure out how fast I'm going.