2013 Terrain Intermittent check engine light

LaMont Owner/Technician Ohio Posted   Latest  
2013 GMC Terrain SLE 2.4L (K LEA Gas) 6-spd (6T45) — 2GKALSEK1D6399780
P0651 — Sensor Reference Voltage "B" Circuit/Open
Intermittent Check Engine Light

The check engine light comes on on this vehicle intermittently, We've noticed no other symptoms, We've actually not gotten the light to come on after we've cleared the codes in the shop, but it comes on for the customer. The first time it came in it had a P0651 (5 volt reference circuit 2 voltage) stored. This time it had a P0651 and a P15A0 (Fuel Economy Mode Switch Circuit Voltage Too Low), (but if you actually look at the test procedure, the code can set if the voltage is too low or too high). I've attached the pertinent freeze frame data for the P0651 code. What we've noticed is that the reference voltage for the circuit 2, 5 volt circuit is 5.5 volts but the reference voltage for circuits 1,3,and 4 are 5 volts. While driving we notice a spike on circuit 2 data of .1 volts. From what we can determine from the repair information the code will set if the voltage will go over 5.2 volts. We saw another post where system voltage was too high resulting in a problem. Our system voltage in freeze frame was 14.39 volts. 

Our questions are:

Has anyone seen this particular problem?

How can circuit 2 voltage be higher than the other 5 volt circuits? 

Could something be inducing extra voltage into the signal wire?

Could this possibly be a bad PCM?

Joseph Technician
South Carolina

LaMont, I can't remember my exact test procedure that I followed it's been several months since I have seen one. But every one ended up being the fuel economy switch with that code and the rise in reference voltage. I remember the first one I unplugged the switch and I think everything came back to normal in data and I am pretty sure I double checked at one of the other sensors it feeds, if I…

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Terry Diagnostician

LaMont; I’m with Joseph, it makes most sense. As you have no other problems, namely a crank circuit, brake pedal position or a AIR injection solenoid?? You could unplug any one of those to see if the 5. Ref comes back into spec. Possible pcm, I would check to see if all 4 areas have the 5.5v reading. T …

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Paul Owner/Technician
New Jersey

I think you need to check the switch probably no good​.​if the vehicle interior is squeaky clean that mean cleaner had been sprayed on lithe switch or soda spill

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Victor Owner/Technician

Check battery condition and charging system integrity.

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LaMont Owner/Technician
LaMont Update

Thanks for the comments. We looked at the console for any sign of something being spilled on it and it does appear that something has been spilled. It takes about 1 1/2 hours to get to the switch, as the console has to come apart. We considered trying to replace the switch with a suitable resistor and having the customer take it and see if the code resets, but because of the labor involved and…

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