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Discussion Starter · #1 ·
I have a 2012 Canyon with I5 engine. 6 months ago it would not crank. This happened over a period of a few days and about 2 dozen attempts at cranking. I tried it with the headlights on and blower on full and they stayed on with no reduction in brightness or fan speed. I know that normally these loads are turned off when the ignition switch is in the start position so this seems odd to me. The starter motor and circuit checked out OK when I jumped the starter relay. I tried swaping similar relays from other circuits to the starter and run/crank positions but this did not change the condition. When it began working again I tested the neutral safety switch and it appears this is working OK. The lights and blower fan turned off when in the start position and the transmission is in gear which is a normal condtion.

It is intermittent because when I go to troubleshoot the circuits in the underhood fuse box (pulling starter and run/crank relays and probing or jumpering the pins) the problem fixes itself. It fixed itself so that it worked with no issues for 6 months. Now recently I had another crank attempt fail. I tried a dozen times but again while I was probing and jumping the relays it fixed itself.

The fact that it is intermittent makes it impossible to track the cause. Is there any common failiure history with this condition that could help me go right to the problem? I'm leaning toward thinking the start position of the ignition switch has a problem. But in my experience this is pretty rare in most vehicles.

Does the PassKey antitheft system allow the engine to crank but not start? My understanding is that it disables the fuel pump so the engine will crank but not start.
 

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Typically the no-crank issues are from the Pass-Lock anti-theft system but you'd know via the flashing "Lock" symbol on the dash. Given your description I'd check the two grouped grounds on your fenders. They are terminating black plastic end caps with a bunch of ground wires going to them with a 10mm bolt holding them to the fender near your air box on one side and by the battery on the other. They didnt remove the paint from the factory before attaching the grounds so cleaning that up tends to resolve a lot of problems for our truck but I'm unsure if the start circuit is involved with that.

When probing or jumping live wires, its common to create a spark gap just before making contact with the other terminal. This creates a momentary high current discharge which may be enough to jump again further down the line where your issue is.

I'd go a step further and clean your battery terminals, and both terminals of the main fuse between the battery and fuse box.
 

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Discussion Starter · #3 ·
Typically the no-crank issues are from the Pass-Lock anti-theft system but you'd know via the flashing "Lock" symbol on the dash. Given your description I'd check the two grouped grounds on your fenders. They are terminating black plastic end caps with a bunch of ground wires going to them with a 10mm bolt holding them to the fender near your air box on one side and by the battery on the other. They didnt remove the paint from the factory before attaching the grounds so cleaning that up tends to resolve a lot of problems for our truck but I'm unsure if the start circuit is involved with that.

When probing or jumping live wires, its common to create a spark gap just before making contact with the other terminal. This creates a momentary high current discharge which may be enough to jump again further down the line where your issue is.

I'd go a step further and clean your battery terminals, and both terminals of the main fuse between the battery and fuse box.
 

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Discussion Starter · #4 ·
Just to be clear that I understand the Pass-Lock system in this truck; if this were to fail the starter would not crank at all? In the 90s GM vehicles they used a resistor chip in the key that was different values for different cars. I see there is no resistor in our key. Are they using an RFID chip embedded in the plastic part of the key?
 

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You are correct in your initial post on the passlock allowing the engine to crank but not start. I've been plagued by this issue intermittently and it doesn't seem like yours. I'll have a flashing lock symbol and there's nothing I can do to drive it for about a half hour. It will sound like it's trying to start but out of gas. I have to leave the ignition in the on position, wait 20+ minutes, then when the lock turns off I'm good till next time
 

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Typically the no-crank issues are from the Pass-Lock anti-theft system but you'd know via the flashing "Lock" symbol on the dash. Given your description I'd check the two grouped grounds on your fenders. They are terminating black plastic end caps with a bunch of ground wires going to them with a 10mm bolt holding them to the fender near your air box on one side and by the battery on the other. They didnt remove the paint from the factory before attaching the grounds so cleaning that up tends to resolve a lot of problems for our truck but I'm unsure if the start circuit is involved with that.

When probing or jumping live wires, its common to create a spark gap just before making contact with the other terminal. This creates a momentary high current discharge which may be enough to jump again further down the line where your issue is.

I'd go a step further and clean your battery terminals, and both terminals of the main fuse between the battery and fuse box.
There are lots of gremlins in these colorados. I had a pass lock issue for years on my 2010 Colorado V8 4x4 Crew Cab. I changed all the Negative grounds, the HVAC control system head unit, the ignition, batteries. Nothing worked until I changed out the HVAC blower motor. I’ve not had a no start for 3 years now. Amazing. Go figure! If the truck starts after 10 minutes of being left alone. It’s a pass lock problem. Change out blower motor. I know it makes no sense, but. Gremlins exist.
 

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I had a similar problem. Would not start / windows acted weird. But sometimes it would. My mechanic couldn't figure it out, so I took it to the dealer. It was a BCM (body control module) and they also replaced the ignition. Hope this helps.
 
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