Cranky SUV got hot under the hood
Dear Tom and Ray:
On a cross-country summer trip to Las Vegas, we stopped for gas in a town in New Mexico. After filling our ’04 Ford Escape, it would crank, but would not start. After a few attempts, I decided to stop so as not to kill the battery. Just down the road, there was a truck repair station. I gave them a call and the owner towed my car into his shop. As he worked on it, it did start up. He hooked up a scan tool, but could find no codes to indicate that anything was amiss. As he was checking under the hood, he put a wrench on the battery clamps, and he said he found that the ground side was loose. He said that could have been what kept the car from starting. After paying the man, we drove to our destination and back to the East Coast with no problems. A friend of mine said that what the guy told me was impossible, and that a loose ground wire would not stop the car from starting. What is your opinion? — Charlie
RAY: A loose ground cable certainly can cause your car not to start, Charlie. But not in the way that your car didn’t start.
TOM: If the ground cable was so loose that it was no longer making contact with the battery post, the car would do nothing when you turned the key. You said your car cranked, but then failed to start. So we know battery power was getting to the starter motor.
RAY: So something else
caused your car not to start.
TOM: If I had to take a wild guess, I’d suspect the crank angle sensor.
RAY: We’ve seen the crank angle sensor misbehave under very hot conditions. And that’s exactly what you were dealing with. You were driving across the country, so you presumably had been on the highway for hours — maybe all day. You were in the southwest desert, and we know the desert can be, what? Hot! You stopped the car, and shut off its cooling functions, while you got gas. That’s what we call a “hot soak” condition, where the engine temperature spikes.
TOM: I’m guessing that the heat caused an open circuit in the crank angle sensor, which sits in the hottest part of the engine, near the flywheel. The sensor then sent an erroneous signal to the car’s computer, and that’s what prevented it from starting.
RAY: After you had it towed, it cooled off enough to restart. And those exact circumstances weren’t duplicated during your trip.