Thread: 2000 Grand Prix Tachometer/Trac Light/Stall Issues

For the past year or so, my 2000 Grand Prix that has 140k miles started having this issue, where I will just be driving a long and all of the sudden, the tachometer shuts off and goes to 0 and the trac light comes on...About the same time this happens, the engine hesitates. To keep it going, all I have to do is pump the accelerator a little bit.

At first, this was happening very rarely, however it started getting more frequent and at times even shut off completely. I would have to wait about 5 minutes before it would start back up and act normal again. I took it to the shop and they determined that the fuel pump relay switch was getting overheated, so they replaced it.

This seemed to help the issue up until recently (been about 5 months since then), but it has started doing it again...Now it is almost every time I drive it.

Does anyone have any ideas? The last thing I want to do is take it to the shop again and them just start replacing things aimlessly.

Thank you for any help that you can offer.

I would say it is a failing CPS or CPS (Crank shaft position sensor or Cam shaft position sensor.) The cam positin sensor is on the timing cover and the crank shaft position sensor is behind the harmonic balancer.

Originally Posted by Liquifire

I thought there was a way to modify the fuel relay to improve it? bending part of it....someone help me out here, as I have never done this personally.

Now if the relay is bad you can bend pin# 85 (I think) out of the way. But usually when the relay goes out then the car does not run. I have never heard of this being associated with a tachometer not working and don't see how it could be.


But good point. It could be part of the stalling issue if that was all he was seeing.

Originally Posted by Liquifire

true.......I have no idea how the tach ties in at all unless somehow the vehicle PCM actually kills the motor for just a tick

Yeah. I know when you hve a bad CPS the car does studder for a minute then the tach falls to zero. But on the other hand I have heard of random stalling issues when the FP relay goes out.

That's why I went with the CPS

Sometimes the engine shuts off entirely WHEN the tach goes to 0, however most of the time it is just the tach and the trac light that come on. I have noticed that when the tach and trac light do their thing, my engine often skips or hesitates like it is going to die, and I am able to keep it from doing that by pumping the accelerator. After this takes place, the trac light stays on and the tach stays at 0 regardless of actual RPMs.

I think the problem with it not starting was due to the relay, however that has since been replaced and it has only done that a couple times. The main issue now is the tach/trac light thing and the engine skip. The last thing I want is to end up on the side of the road, unable to start it.

With the CPS, would that be expensive and/or difficult to replace and/or check myself?

I'm not sure how to check the CPS. But it is fairly easy to replace if you have hand toold and stuff.


I find it odd that the Trac light is coimming on when this happens.

Also some good points.

I was having the exact same issues except for the trac light thing. it was like the car would run good but occasionally the tach would drop to zero, but then it would stall idling, it started happening more frequently so i replaced the crank.P.S. thanks to some suggestions from my thread and i dont have any of those issues now.

Pacothetaco, was the CPS difficult to replace and how much? Thank you for all the tips guys...I may go ahead and try to replace the CPS and see where that takes me...Is there anything else that I should try while I'm doing that?

It's beind the harmonic balancer. You will have to take the passenger side wheel off and use an impact to get the balancer bolt off.


Thn you will need a puller. Do not use the JAW type. Use the bolt type.



You will need to take the crank bolt out. The go to lowes or home depo and buy 3 M6 - 1.00 75mm bolts and some washers to fit those bolts. Then make sure that the puller's main bolt goes all the way inside of the crank and does not hit the threads. Usually the main bolt size for the pulley is smaller than the inside dia of the female crank bolt hole.


Some pullers have a cone shaped peice that goes on the end of the main bolt for the pulley. If you can take that off then you could more than likley do it like i stated above. If not you'll have to put a deep socket where the crank bolt goes.


Then all you do is thread those three bolts through the slots in the ballancer. The washers are to prevent the head of the bolt from going through the slots in the puller. Usually the head is about the same size as the slots and when you're trying to pull it they will slip through.


If you need anything else just let me know buddy.

funny, my car did the same thing tonight: Qik | Daniel Brincat | Untitled

Tach at 0, TCS Light on....

Looks like I'll be replacing the CPS soon. Thanks for the info.

Thank you all a whole lot. Sorry it took me so long to post again, but this did indeed fix the problem. It kills me that it was such an easy fix, which could have lead to hundreds of dollars at a shop trying to diagnose.

Thanks again guys, I really appreciate it

tai27yiuop, did you figure out the issue? I have this EXACT issue - my tach goes to zero and the traction light comes on at the same time. I restart the car and tach functions just fine and traction light is off. It has been happening for months, but then a couple times lately I got a check engine light - plugged in the reader and the code pointed to CPS, so I'm thinking maybe that's in my future to replace this...

Originally Posted by Oxfire

Replace it. I have the same issue and am going to replace mine tomorrow. Shouldn't be too expensive.

I plan on replacing it, but I'm moving out of my apartment into a house with a garage, so I won't get to it for a few weeks yet. I'm not too worried, I've been noticing this issue for months and months - I think it's failing very very slowly. I don't want to push my luck, but I think I can wait until I have all my tools setup in my garage.

I did replace my power window motor & regulator last night because it was supposed to rain today and the window started falling down earlier this week. Now it's a really sunny day it looks like, lol.

How hard is it to replace the CPS? I read on this thread and a few other places I need to get a pully removal tool from the autoparts store and pickup a few bolts and remove the passenger's side front wheel to get to where the sensor is?

Any good video or walkthrough with some pictures that someone can link to this thread? I only have managed to find text descriptions so far. Thanks!