Pretty common problem with these. Here's a guide to learn how to fix GM instrument clusters yourself, I used it to fix mine and it worked great.How to guide for H2 instrument cluster repair
Commonly in 03-06 GM vehicles such as your Hummer the speedometer stepper motors will fail causing your gauges to stop working. Visit this link for more information on hummer instrument cluster problems
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Pretty common problem with these. Here's a guide to learn how to fix GM instrument clusters yourself, I used it to fix mine and it worked great.How to guide for H2 instrument cluster repair
This is a solitiation for a service not a how to do it as it says.
Commonly in 03-06 GM vehicles such as your Hummer the speedometer stepper motors will fail causing your gauges to stop working. Visit this link for more information on hummer instrument cluster problems