Conditions for 2008 Silverado seat heater circuit to cut out.

[bobejones]

I assume if there are any real techs here, you have dealt with seat heaters.  Would like to get down to the technical aspect so I can correctly troubleshoot the issue. 

 

Condition - Drivers heat buttons activate, confirmed audible relay switching under the seat.  All lights on buttons work.  After approx 2-4min of either depressing "top heat" or "top/bottom heat", I hear an audible click of a relay from the BCM are associated area, and seat button lights go out.  If pressed again, they will light up but conditions will just repeat.  I do not detect any heat from the seat but it usually takes some time.  

 

Have confirmed passenger heaters function and heat normally.

 

Tests

1.  Found a 2 pin plug so far between drivers seat and center console.  One side seems to be a resistive heater as it reads 6ohms. 

2.  Other side side of 2 pin plug is showing battery voltage when heat switch is hit.  

 

 

 

Have not been able to find the other plug to confirm if dead or not and unable to confirm which heat element I tested. I am curious of the conditions for the truck to shut down the heater?  It does not appear the heaters have any thermostat?  So is the BCM looking at current to determine normal operation?  Some have mentioned a "short" but that is highly unlikely IMO as resistive heaters typically fail open from a broken wire.  I would just like to confirm a diagnosis due to all the time required to take the seat apart.  

 

I am a little baffled why a relay fires under the seat, but sounds like the BCM is what is shutting down power to the seat.  I do know for a fact the BCM already has issues and I have traced an issue with the fog lights to a faulty output from the BCM, so I cannot rule out a BCM issue just yet.  

 

[Doug_Scott]

Don't know how it is supposed to work, but, have noticed that on the internet, people will call anything wrong with wiring "a short".  

 

The seat heaters pretty much have to run from a relay.  The BCM is likely what controls the relay, by either applying voltage to the switch side of the relay, or being the ground for the relay.  When you tested the resistance and got 6 ohms, was that to ground, or across the two pins?  You should try to locate a wiring diagram for your truck.  It will make it a lot easier to diagnose.