Eric’s 2003 Chevy Avalanche, Still Starting Two And A Half Years Later

The question we get more than any other is not “will it work”. It is “will it still be working in three years”. Fair question. Most of the fixes these owners have already tried worked beautifully for a week or a month before the problem came back.

Eric L. Knowlton bought a NEWROCKIES PRO Module for his 2003 Chevrolet Avalanche in July 2014. We know how that turned out because he kept telling us, in public, for the next two and a half years.

September 2014, seven weeks in

“Thanks guys! The 2003 Avalanche is still starting every time! You saved my summer and fall fishing season!”

Seven weeks is not a long test. But note what he chose to measure it in. Not miles, not starts. A fishing season. That is what an unreliable truck actually costs you: not the repair bill, but the things you stop planning because you cannot count on the vehicle getting you there.

January 2017, he starts sending us his friends

Two and a half years later, Eric turned up in the comments again. This time he was not talking to us. He had tagged two friends on one of our posts to tell them that this was what he had used when his 03 Avalanche locked out its own starting because of, in his words, passive security from GM.

Nobody recommends a repair to their friends thirty months later unless it held.

February 2017

“Thank you again – I continue to tell my friends about you and your product, especially GM owners. Great vehicles, crappy passive security system.”

That last sentence is the whole argument in six words. These are good trucks. The Avalanche is a genuinely well built vehicle that will run for three hundred thousand miles. The part that fails is not the engine or the transmission. It is a security system that was designed to be tamper proof and ended up being failure prone instead.

Why the fix does not degrade

On a 2003 to 2006 Avalanche the Passlock sensor lives in the ignition lock cylinder. A small magnet on the lock rotates past a Hall effect sensor as you turn the key, and the sensor sends a coded voltage signal down to the Body Control Module. The BCM compares that signal to the value it learned, and only if the two agree does it tell the engine computer to deliver fuel.

Everything in that chain wears. The sensor drifts, the thin signal wire flexes with the tilt column until it fractures inside its insulation, and the connector oxidises. The BCM does not know any of that. It only knows the number it is reading no longer matches, so it shuts the fuel off and lights the SECURITY lamp. The truck cranks perfectly and will not run.

This is also why the workarounds expire. A resistor spliced in, a relearn procedure, a new lock cylinder: each of these restores a matching value for a while, and each of them puts the same fragile comparison right back in charge of whether your truck starts tomorrow.

The PRO Module removes the comparison itself. There is no signal being measured, so there is no value left to drift out of range. That is why Eric’s answer in February 2017 was the same as his answer in September 2014. There was no mechanism left by which it could get worse.

And the fishing clearly never stopped: these days Eric turns it into art. His hand-carved fish work is at Reel Trout Studio on Etsy, and it is worth a look.

If you have one of these trucks

The Avalanche shares its Passlock hardware and its BCM location with the same era Suburban, Tahoe, Yukon, Sierra, Escalade and Silverado Classic. The BCM sits in the dash directly under the steering column, behind the trim panel. The wiring, connector by connector, is here: 2003-2006 Chevrolet Suburban, Tahoe, Avalanche, GMC Yukon and Sierra, Cadillac Escalade, 2003-2007 Silverado Classic.

Related stories on the blog. Same platform, same years: Dan’s Yukon XL and Scott’s Suburban.

Read more customer stories →