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Jared D
Jared D, ASE Certified Technician
Category: GM
Satisfied Customers: 1773
Experience:  Shop Supervisor at County Fleet
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I need help diagnosing and fixing my 2003 Hummer H2 heated

Customer Question

I need help diagnosing and fixing my 2003 Hummer H2 heated seats
JA: Have you checked the coolant level? Has there been any leaking from the hoses?
Customer: They are electrically heated seats
JA: Are you fixing your H2 yourself? What have you tried so far?
Customer: only fuses. seats started working only sometimes then not at all. Both seats do this at the same time. I think electrical issue
JA: Anything else you want the mechanic to know before I connect you?
Customer: Just help with the seats.
Submitted: 8 months ago.
Category: GM
Expert:  Jared D replied 8 months ago.

Hi,

Can you run the following tests? You will need a multimeter.

Check for the relay in the Memory Seat Module (MSM) to click when the heated seat button is pressed.

If it does, disconnect the MSM.

Test the resistance of the seat heater elements from the MSM connector. They should all be 1.5-5.5 ohms.

If ok, have an assistant sit in the seat and retest.

Check each circuit for continuity to the seat frame. There should be no continuity- your meter should read ol when set to ohms.

Customer: replied 8 months ago.
I can test if you tell me where the module is located. I need help starting from scratch. Like I stated the seats used to work fine then went intermittent and now do not heat at all.
Expert:  Jared D replied 8 months ago.

Here is a diagram of the heated seat. The module is #3 and 4.

Expert:  Jared D replied 8 months ago.

Here are the two connector maps you will need for #3 and 4.

Expert:  Jared D replied 8 months ago.

You will check from pin 1 of connector 3 to pin 2 of connector 4 for resitance between 1.5-5.5 ohms. Then also from pin 11 to 13 of pin 4 for resistance.

Expert:  Jared D replied 8 months ago.

I'm sorry C3 pin 1 to C4 pin 14 (not pin 2).

And C4 pin 2 to C4 pin 11. I was looking at the diagram wrong.

Expert:  Jared D replied 8 months ago.

Next C3 14 to C4 12 for resistance. It should be 1.5-5.5 ohms.

And C4 22 to C4 1- also 1.5-5.5 ohms. These two are the seat back heaters.

Expert:  Jared D replied 8 months ago.

I just wanted to check whether you still need help with this.

Please don't forget to rate.

Expert:  Jared D replied 8 months ago.

Please don't forget to rate.