P0690 Code help

[ween]

There shouldn't be that much voltage drop across the relay contacts
Ignition on: 30 12v, 85 12v, 86 ground, 87 6.3v
The voltage at terminals 30 and 87 should pretty much be the same with the relay operating.

[rcarson25]

So I re ran the checks as suggested.

Ignition on: 30 12v, 85 12v, 86 ground, 87 12v
Ignition off : 30 12v, 85 0v, 86 open circuit, 87 7v.

I tested the wire that comes into the fuse block at 87 with the relay out of the fuse block. There is 7v there when the car is off and 6.3v when ignition is on. Should there be voltage at this wire with the car off? Does low voltage there when off indicate a short or a back feed?

[ween]

I'd have to check on a similar system. The voltage checks would normally be done with the relay in circuit.
GM tells you to use 2011 or so Camaro for service information. The powertrain relay is wired differently in the Camaro compared to the GMPP.

[ween]

Checked on a vehicle in shop today, had LS7. Removed Powertrain relay, cycled ignition, left off, probed terminals.
Term 30 12.7V, Term 87 0V, Term 86 12.6v, Term 85 0V. Cleared P1682 code afterwards.
This vehicle has the GM trans computer that plugs in to the bulkhead connector.
I feel something is suspect with your harness. Is there anything connected to your bulkhead connector?
According to GM instruction sheets, the LS engine control kits all use the same engine harness.

[rcarson25]

Kind of as I suspected I seem to be getting some sort of power feed back into the harness. Of course the bulkhead connector in question is buried deep within the fender well and will not be easy to get to. Would have to pull the whole fender to get to it . Thanks so much for the confirmation, I assume that 6v I am seeing at the pin 87 wire with Ignition off is my issue. I will track it down and at least I know where to start. Any clue what in the bulk head may tie to the wire that feeds pin 87 on the Pt relay?

[ween]

Can't say. Quick test would be to remove the fuses labeled bulkhead in the GMPP fuse/relay box though.

[rcarson25]

Yeah I plan on pulling some fuses to help track this down. Hopefully I can track this issue down.

[rcarson25]

So after testing a few fuses and relays I think I have found the issue. Relay 3 for the dual fan setup has a constant 12v wired to pin 86 and it should be a 12v switched. When that relay is out of the equation the P0690 and the 7v at pin 87 of the PT relay is gone. Have to open up the fuse block and change the wire, fingers crossed I can get to it without taking too much apart.

[rcarson25]

Made the change in the fuse block and all is good. No more check engine and no more phantom voltage at the PT relay. Thanks for all the help.