003 Yukon XL, 86,000 miles
So, for a while now I've had the typical bizarre seat control behavior that needs to be addressed by a seat module software update by the dealer (PIT3598). Some times the forward/reverse on the driver's side didn't work and sometimes it was reversed (i.e. push forward to go back and vice versa) but everything else worked (Passenger side seat controls, both seat heaters, lumbar, recline, etc) so I wasn't in too much of a hurry to have it fixed. I avoided moving the seat much just in case it didn't feel like working the next time. The other day I was driving to work with my seat heater on and I moved the seat a bit when everything stopped working (Heaters stopped, couldn't move my seat or the passenger seat at all).
After work when I was driving home I thought I kept smelling a burning plastic smell but I couldn't be sure. I grabbed a hold of the 30 amp breaker to the bottom left (Which was supposedly for the seat controls) of the panel near the brake pedal and it was so hot it literally blistered my thumb and forefinger. I used a screwdriver to pop it out and the plastic around one leg was brown from heat.
I figured this could no longer just be a "software anomaly" and that a wire must have been rubbed raw and grounded out when I moved the seat. I pulled the seat bottom off and looked over everything and saw no obvious problems but good lord is that a complex mechanism that makes me want to revert to manual controls. I reinserted the breaker with the harness disconnected and it didn't get hot or spark. I checked for voltage at the connector from the floor to the seat controls and got 12 volts. After reconnecting everything if I put the breaker back in it gets hot just like before. I also tried disconnecting the passenger side seat and got the same result.
I connected another 12 volt battery directly to the + and - on the driver's seat plug and the conductors immediately got hot. That at least proves it's not a + wire grounding out due to worn insulation since that battery had no path to chassis ground. So, it's either the + and - making direct contact somewhere or it's the seat module itself. I should have done it before but I checked continuity across the + and - and got 0 ohms so something isn't right.
Any ideas? Is my seat module fried? Is this something that could still be fixed by PIT3598? I don't want to bring it to the dealer for PIT3598 (1 hr of labor) and end up paying dealer pricing for a replacement seat module and labor ($300+ easy) that I could have pulled from a junk yard and plugged in myself for <$50.
---------- Post added at 06:51 PM ---------- Previous post was at 06:20 PM ----------
Well, after typing that up I realized that the obvious thing to do was to remove the module completely and test continuity between the + and - terminals. 0 ohms with everything disconnected so it's definitely the module and not something downstream. I pulled open the plastic housing and there's no apparent damage to the components or the PCB. There are several relays on the board that could be the problem I suppose but I expected to see charred components.
I guess I'll swing by the junkyard and hope to find an '06 (Since they have the updated firmware) with 6 way seat controls with the module still intact.
So, for a while now I've had the typical bizarre seat control behavior that needs to be addressed by a seat module software update by the dealer (PIT3598). Some times the forward/reverse on the driver's side didn't work and sometimes it was reversed (i.e. push forward to go back and vice versa) but everything else worked (Passenger side seat controls, both seat heaters, lumbar, recline, etc) so I wasn't in too much of a hurry to have it fixed. I avoided moving the seat much just in case it didn't feel like working the next time. The other day I was driving to work with my seat heater on and I moved the seat a bit when everything stopped working (Heaters stopped, couldn't move my seat or the passenger seat at all).
After work when I was driving home I thought I kept smelling a burning plastic smell but I couldn't be sure. I grabbed a hold of the 30 amp breaker to the bottom left (Which was supposedly for the seat controls) of the panel near the brake pedal and it was so hot it literally blistered my thumb and forefinger. I used a screwdriver to pop it out and the plastic around one leg was brown from heat.
I figured this could no longer just be a "software anomaly" and that a wire must have been rubbed raw and grounded out when I moved the seat. I pulled the seat bottom off and looked over everything and saw no obvious problems but good lord is that a complex mechanism that makes me want to revert to manual controls. I reinserted the breaker with the harness disconnected and it didn't get hot or spark. I checked for voltage at the connector from the floor to the seat controls and got 12 volts. After reconnecting everything if I put the breaker back in it gets hot just like before. I also tried disconnecting the passenger side seat and got the same result.
I connected another 12 volt battery directly to the + and - on the driver's seat plug and the conductors immediately got hot. That at least proves it's not a + wire grounding out due to worn insulation since that battery had no path to chassis ground. So, it's either the + and - making direct contact somewhere or it's the seat module itself. I should have done it before but I checked continuity across the + and - and got 0 ohms so something isn't right.
Any ideas? Is my seat module fried? Is this something that could still be fixed by PIT3598? I don't want to bring it to the dealer for PIT3598 (1 hr of labor) and end up paying dealer pricing for a replacement seat module and labor ($300+ easy) that I could have pulled from a junk yard and plugged in myself for <$50.
---------- Post added at 06:51 PM ---------- Previous post was at 06:20 PM ----------
Well, after typing that up I realized that the obvious thing to do was to remove the module completely and test continuity between the + and - terminals. 0 ohms with everything disconnected so it's definitely the module and not something downstream. I pulled open the plastic housing and there's no apparent damage to the components or the PCB. There are several relays on the board that could be the problem I suppose but I expected to see charred components.
I guess I'll swing by the junkyard and hope to find an '06 (Since they have the updated firmware) with 6 way seat controls with the module still intact.
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