Note: The DM is an extra computer module only found on North American models, for USA emissions compliance... it controls the infamous Check Engine Light (CEL) on the instrument cluster. European .034/.036 owners can skip reading this, as Euro-spec cars do not have either the DM or the CEL.
Last night my Check Engine light came on unexpectedly while driving the car. There is a built-in LED and button in front of the CAN box which allows checking the DM blink code. The LED should be off, and it should light up when the button is pressed. Oddly, the LED was on all the time when the ignition was turned on. Pressing the button did nothing, the light stayed on regardless. I connected a digital scanner, and the scanner could not communicate with the module. Curiouser and curiouser! All fuses were ok. So I figured I'd remove the module and re-connect it. When I pulled the module, it was very warm, almost hot... but the car had been sitting for 12+ hours and was stone cold!
Long story short, the module simply died with no warning. Replacing the module with a good used one cured all symptoms. I've never heard of a DM failing before. Thought I'd document the symptoms and the fix here in case someone has a similar issue in the future.
Last night my Check Engine light came on unexpectedly while driving the car. There is a built-in LED and button in front of the CAN box which allows checking the DM blink code. The LED should be off, and it should light up when the button is pressed. Oddly, the LED was on all the time when the ignition was turned on. Pressing the button did nothing, the light stayed on regardless. I connected a digital scanner, and the scanner could not communicate with the module. Curiouser and curiouser! All fuses were ok. So I figured I'd remove the module and re-connect it. When I pulled the module, it was very warm, almost hot... but the car had been sitting for 12+ hours and was stone cold!
Long story short, the module simply died with no warning. Replacing the module with a good used one cured all symptoms. I've never heard of a DM failing before. Thought I'd document the symptoms and the fix here in case someone has a similar issue in the future.
