Grand Prix speedometer jumping and stalling
09-19-2018, 06:38 PM
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Grand Prix speedometer jumping and stalling Hi, I have an 08 Grand Prix GXP with just under 100,000. The problem I’m having is the speedometer jumps when I come to a stop or I am going under 30 mph. My car also stalls occasionally when this happens. I replaced the speed sensor, the battery, and the alternator and nothing has solved the problem. Any help would be much appreciated.
10-02-2018, 01:31 PM
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Unfortunately, it's probably your torque converter/transmission failing. I have an 06 gxp that's been through two trannies now 
The first time it blew it would do this pretty badly, sometimes the speedo would jump to 50+mph while at a light. If you have more questions I'd jump in the ls4 forum section, lots of good info and super knowledgeable people there..
The first time it blew it would do this pretty badly, sometimes the speedo would jump to 50+mph while at a light. If you have more questions I'd jump in the ls4 forum section, lots of good info and super knowledgeable people there..
10-02-2018, 04:14 PM
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I bought the car with 50k on it with a bad trans and had it replaced. I’ve only put 43k on it. I knew they didn’t last long but I figured I’d get more than that out of it.