why does my 1999 pontiac grand prix loss all power when the tempature light comes on

Asked by Jul 06, 2013 at 09:02 AM about the 1999 Pontiac Grand Prix 4 Dr SE Sedan

Question type: Maintenance & Repair

i have replaced the EGR valve, thermastat, thermastat censor, water pump, low coolant censor.. My car is NOT running hot but when driving as soon as the tempature light comes on the car losses all power.

2 Answers


Check your battery connections. A loose or dirty connection can also cause this type of issue.


Found this thread on another site. Might be same issue as yours ---My 1999 Grand Prix has been acting up with all the same symptoms many people described. Engine cut out at highway or low speed; hard to start after a hot shut down; the Trac light stayed on after the engine cut out and immediate restart in neutral etc. It was getting worse lately with the hot weather. I contemplated replacing the crank position sensor, mass air flow sensor, PCM one at a time, and hundreds of $ at a time, like many people before me. Then, I found the way to fix my problem at ZERO DOLLAR! I figured that it could be a voltage problem. I used a multi-meter. I measured the voltage across my battery, which show the normal 12.7 V. But from the positive terminal junction to a good ground on the engine (e.g. Al engine mount) the voltage has dropped down. I also measure the conductivity as well, and I did not get zero Ohm between the negative terminal to the good ground spot on the engine. I removed the grounding cable attached to the body panel and found that it was bolted on to a part with original body paint! What a bad design! Paint is not the best conductor in the world! After years of dirt and rust build-up, the conduction between the bolt threads won't be as good as before. So you get intermittent voltage drops that stalled the engine. I gave the contact a good rubbing with sand paper. I check voltage and conductivity after and it was good as you would expect. Since than, I never had a single staling. It has been three weeks with lots of kilometers in hot weather. I trust that the same remedy will solve a lot of your problems. I apologize to many garages for reducing tens of thousands of dollars of their potential business.

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