James’s 2000 Cavalier: 400,000 km and the Only Fault Left Was Theft Lock

James Woolley is a mechanic, and his April 2014 story involves the highest-mileage car anyone has ever sent us: a 2000 Chevrolet Cavalier that has crossed 400,000 kilometres. The odometer photo is below, because nobody would believe it otherwise.

The $500 Cavalier

“It all started when I found a 2000 cavalier for only $1200, with 385000km mind you. It seemed too good to be true especially when i managed to talk him down to 500. Well, car bought and his issues are now mine. Over the months I found many other issues I didn’t see during my initial inspection. Mostly ok.. I managed to repair all but the darn theft lock happening every now and then. I kept being locked out at random and nothing I could find would help me to fix the issue, I found how to reset the theft lock but that never solved the problem.”

Read that again: a working mechanic fixed everything on a 385,000 km car except the security system. Not because it was the hardest problem mechanically, but because there is nothing to fix. The parts all test fine. The system is doing exactly what it was designed to do, with a worn-out sensor feeding it bad data.

His father’s daily driver

“Since that time I’ve given the vehicle to my father.. it has over 400k km and still runs great. for me to say it runs great means a lot, as a mechanic i’m really surprised it works as good as it does. His only issue is the lockout. tended to happen at least once a week. He’d be ok if he left it for 10 minutes.. then the car would start like nothing was out of the ordinary. But it kept happening. Once a week.. twice.. it happened randomly and drove my father crazy.”

First time, and every time since

“so I found the new rockies module. Installed as per the instructrion for the 2000 cavalier, everything it said is exactly how I found it. When we were done with the wiring and instructions.. the car started first time.. and every time since. I had written it off as a loss given it’s high km, I didn’t really expect the new rockies to work as expected given the issues this car has.. but no problems at all.”

“Everything it said is exactly how I found it” is a mechanic grading the documentation, and we will take it.

Why a healthy Cavalier locks itself out

The 2000 to 2005 Cavalier and Pontiac Sunfire run Passlock: a magnet in the lock cylinder swings past a Hall effect sensor as the key turns, and the Body Control Module compares the resulting voltage against a learned value before it will allow fuel. At 400,000 km that lock cylinder has been turned perhaps a hundred thousand times. The sensor reading drifts, the BCM sees a mismatch once or twice a week, and a mechanically excellent car gets parked for ten minutes at a time by its own anti-theft logic. The ten-minute wait is the system’s tamper timeout, which is why waiting always “fixed” it and never fixed it.

The NEWROCKIES PRO Module removes that comparison permanently, which on this car meant the last unfixable fault on the list got fixed.

If you have a Cavalier or Sunfire

The BCM is under the left side of the dash, and the connector-by-connector wiring is here: 2000-2005 Chevrolet Cavalier, Pontiac Sunfire installation guide.

Related stories on the blog. Two more high-mileage saves: Marty’s Lumina, one decision from the scrapyard, and Trent’s Riviera.

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