96gt4.6

iTrader: (5)

Hey guys, i'm having a heated seat issue with my 2004 Silverado SS that is kicking my butt! My issues is, both my front heated seats are inop, although they both are exhibiting different symptoms. The LH heated seat works for about 2 minutes, then sets DTC B2425 - Left Front Seat Heater Circuit. The RH heated seat indicators will come on for about 1 second then turn right off, and sets DTC B2430 - Right Front Seat Heater Circuit.



So, at this point I was fairly certain that I had a heater element issue. Being as the passenger seat seems to be more problematic, I started there. I unbolted and tipped the driver seat back to access the appropriate connector on the Driver Seat Module so that I could ohm out the passenger heated seat grids (back and base). My results were as follows:

Passenger seat heater base grid resistance: 4.5 Ohms
Passenger seat heater back grid resistance: 8.6 Ohms

According to the factory manual specification, the grid resistance should be between 1.5-5.5 Ohms.

So, it would appear that the heater grids are out of spec on the resistance. I disconnected the grid's under the passenger seat and ohm'd them there just to eliminate a wiring possibility, as well as checked all circuits from the Driver seat module to the connectors under the passenger seat for short to power, ground and together. All circuits from the DSM to the grid connectors under the passenger seat checked out great. Pin fitment on the connectors is good as well, no spread terminals.

So, I removed the passenger seat and broke it down. Both grids looked perfect. However, being as the ohm's were out of spec, I figured they needed replaced. I got two new grids from the GM garage. However, before installing them, I ohm'd them out. They ohm'd out within 1 ohm of my existing grids.....

So, at this point i'm confused! But, it gets better.

I have a friend with the same truck (with working heated seats!) that was kind enough to let me use his for some data. His grid's also ohm close to mine at the DSM connector. So, i'm thinking the factory spec isn't 'precise'.

So, at this point, i'm thinking the DSM is the problem. I swapped out his DSM, and it produces the same fault codes and symptoms in my truck.

So, next up I did some searching on GM's TIS website with my VIN, and look at all the seat heater issues they have an updated software calibration for:



So how the system sets those DTC's by what i'm reading in the service manual, is the DSM is constantly monitoring the resistance of the grid's on that seat, and if it falls outside of a set resistance window, the seat is disabled and the DTC is set. I see on GM's TIS webside, that one of the software updates pertains to the false setting of heated seat DTC's and open/short circuit detection.

Looks like I need to get my DSM's software level checked before proceeding. Any GM tech's in here possibly that can help confirm?

AKlowriderZ71

iTrader: (22)

Did you find any overheated or burnt terminals on the seat's main harness connectors?

96gt4.6

iTrader: (5)

I did, both C320/305/399/326 all appear good.

Those resistance readings were taken at the DSM, which is the resistance of the entire heater loop(s).

Although 'out of spec' according to the service manual (1.5-5.5 ohms), my comparison truck functions fine with element loops that are also out of spec. However, mine is about 1-2 ohms higher on the seat back element (8.6 ohms) than the comparison truck.

I also forgot to note, if I use the scanner to run the heated seats via the output controls, the seat(s) heat fine both back and base.

It's almost like the DSM is being overly cautious of the resistance of the heater loops, and setting the DTC's/shutting off the system due to that.

1FastBrick

iTrader: (17)

Most likely it needs the updated calibration.

Can you read the current calibration in that module?

96gt4.6

iTrader: (5)

It should also be noted the seat back sensor readings are within spec as well before, and during the concern. Commanding the seat to heat via scan tool and watching the PID shows that the reading is valid going fom 4.0V to 2V after about 5 minutes of operation, in addition to the seats becoming physically warm.

AKlowriderZ71

iTrader: (22)

Is there a newer calibration available thru TIS?

1FastBrick

iTrader: (17)

See bottom of first post...

96gt4.6

iTrader: (5)

I believe so. Refer to my original post, there is a screenshot from the TIS Web app showing all the calibration updates available, however I have no way of checking what's on my DSM currently. I will most likely have to contact the dealer to get the DSM calibration checked/updated before I proceed.

1FastBrick

iTrader: (17)

What version of software is your Solus on?

AKlowriderZ71

iTrader: (22)

I'd start with the calibrations.