P1682

[Glisella]

Anyone have any experience with this one?

2008 Yukon XL Denali (6.2L)

I go out to leave today, and it starts but I notice CEL is on. I turn off, go to garage and get my hand scanner and see P1682. Quick Google search says maybe ignition switch and to check relays...so I check the Power train, starter and ignition relays and they're all good. I get back in and go to start it and it won't...it won't even crank. Full electric is working; radio, lights, gas and battery gauges are responsive. New starter and two new batteries installed couple months ago.

Maybe the ignition switch since relays/starter/batteries are good?...something else to look at?

 

[Doubeleive]

I would check the bcm harness for any corrosion, maybe clean the harness up regardless and see if that fixes the issue

 

[swathdiver]

Anyone have any experience with this one?

2008 Yukon XL Denali (6.2L)

I go out to leave today, and it starts but I notice CEL is on. I turn off, go to garage and get my hand scanner and see P1682. Quick Google search says maybe ignition switch and to check relays...so I check the Power train, starter and ignition relays and they're all good. I get back in and go to start it and it won't...it won't even crank. Full electric is working; radio, lights, gas and battery gauges are responsive. New starter and two new batteries installed couple months ago.

Maybe the ignition switch since relays/starter/batteries are good?...something else to look at?

P1682 - Ignition 1 Switch Circuit 2

CIRCUIT/SYSTEM DESCRIPTION

There are 2 ignition 1 voltage circuits supplied to the engine control module (ECM). The first ignition circuit is
provided by the powertrain relay, through a fuse. This ignition 1 voltage circuit supplies power to all the
internal ECM circuits associated with the throttle actuator control (TAC) operation. The second ignition 1
voltage circuit is supplied by the run/crank relay through a fuse, and is used to power the remaining internal
ECM circuits. If the ECM detects a voltage difference between the 2 ignition 1 voltage circuits, DTC P1682
will set.

CIRCUIT/SYSTEM TESTING

Testing the Ignition 1 Signal Circuit
1. Ignition ON, verify that B+ is available to both test points of the fuse from the powertrain relay to the
ECM.
 If B+ is only available on one test point of the fuse, test the ignition 1 voltage circuit from the fuse
to the ECM for a short to ground. If the circuit tests normal, replace the ECM.
 If B+ is not available on either test point of the fuse, replace the underhood fuse block.
2. Ignition OFF, disconnect the ECM C1 connector.
3. Ignition ON, verify that B+ is available at C1-19.
 If B+ is not available, test the ignition 1 voltage circuit for an open/high resistance condition. If the
circuit tests normal, replace the ECM.
4. If all circuits test normal, replace the ECM.
Testing the EC Ignition Relay Feedback Circuit
1. Ignition OFF, remove the powertrain relay from the underhood fuse block.
2. Ignition ON, connect a 3A fused jumper wire from B+ to the powertrain ignition 1 voltage circuit
terminal. Verify that the EC Ignition Relay Feedback parameter displays B+ on the scan tool.
 If the scan tool parameter is less than the specified value, test the ignition 1 voltage circuit for an
open/high resistance or short to ground. If the circuit tests normal, replace the ECM.

 

[Glisella]

So today I go out and try to start car and it cranks for maybe an extra half second more than normal and it starts up. Reminder yesterday it wouldn't crank or click or anything.

No CEL light (I did not clear yesterday) and I never got chance to clean any harnesses or anything else.

So for now this will be filed under "weird stuff my truck did". Will bring this thread back if it happens again.

 

[thompsoj22]

P1682 - Ignition 1 Switch Circuit 2

CIRCUIT/SYSTEM DESCRIPTION

There are 2 ignition 1 voltage circuits supplied to the engine control module (ECM). The first ignition circuit is
provided by the powertrain relay, through a fuse. This ignition 1 voltage circuit supplies power to all the
internal ECM circuits associated with the throttle actuator control (TAC) operation. The second ignition 1
voltage circuit is supplied by the run/crank relay through a fuse, and is used to power the remaining internal
ECM circuits. If the ECM detects a voltage difference between the 2 ignition 1 voltage circuits, DTC P1682
will set.

CIRCUIT/SYSTEM TESTING

Testing the Ignition 1 Signal Circuit
1. Ignition ON, verify that B+ is available to both test points of the fuse from the powertrain relay to the
ECM.
 If B+ is only available on one test point of the fuse, test the ignition 1 voltage circuit from the fuse
to the ECM for a short to ground. If the circuit tests normal, replace the ECM.
 If B+ is not available on either test point of the fuse, replace the underhood fuse block.
2. Ignition OFF, disconnect the ECM C1 connector.
3. Ignition ON, verify that B+ is available at C1-19.
 If B+ is not available, test the ignition 1 voltage circuit for an open/high resistance condition. If the
circuit tests normal, replace the ECM.
4. If all circuits test normal, replace the ECM.
Testing the EC Ignition Relay Feedback Circuit
1. Ignition OFF, remove the powertrain relay from the underhood fuse block.
2. Ignition ON, connect a 3A fused jumper wire from B+ to the powertrain ignition 1 voltage circuit
terminal. Verify that the EC Ignition Relay Feedback parameter displays B+ on the scan tool.
 If the scan tool parameter is less than the specified value, test the ignition 1 voltage circuit for an
open/high resistance or short to ground. If the circuit tests normal, replace the ECM.

Wow! what a reply, I have got to get the tech2 and a subscription to the service manuals and im sure i could comply with this troubleshooting sequence. I have simply been apprehensive in regard to the tech2 based upon unknown sellers and the fact that the tech2 is a perfect example of how china is guilty of ripping america off and stealing our technology. But i cant deny my family the benefit of repairing our own vehicles because american manufacturers feel the tech2 should sell for $3k-$5k and only be afforded to stealerships! To the OP, if you were well versed and knew all the component locations you could probably diagnose your issue in 30 minutes! hope it works out easy/accurately.

 

[swathdiver]

Wow! what a reply, I have got to get the tech2 and a subscription to the service manuals and im sure i could comply with this troubleshooting sequence. I have simply been apprehensive in regard to the tech2 based upon unknown sellers and the fact that the tech2 is a perfect example of how china is guilty of ripping america off and stealing our technology. But i cant deny my family the benefit of repairing our own vehicles because american manufacturers feel the tech2 should sell for $3k-$5k and only be afforded to stealerships! To the OP, if you were well versed and knew all the component locations you could probably diagnose your issue in 30 minutes! hope it works out easy/accurately.

I agree, it was not apparent to me at first. As much as I try, I cannot get everything wanted made in America within our budget. But we have made great strides.