Medium and Heavy Trucks
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Hi my name is ***** ***** will be glad to help. What is the year make and model of the truck this is in and also the first three digits of the engine serial number (Prefix) ?
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What symptoms are you having? If the engine wont start and there is no check engine light then check the inline fuse between the batteries and ECM as the ECM has likely lost power. If everything is okay and operation is normal but the check engine light does not come on it could be the bulb itself in the cluster. Let me know
Pin 28 wire 994 YL
I took a snapshot of that area of the schematic. One lead is from battery and the other from the 994 YL wire
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Hi, I had to go out on a road call. I help on here in between jobs and nights as I am available. The broken dotted lines are ground. The solid line is power and the other gets grounded through the ECM when the ECM commands the light on. Test for ground at that pin 28 through the ECM when you unplug some sensors to throw a code.
Constant power at pin 28? Try Grounding the 994 YL wire on the ECM side of the light. See if the light comes on. If it does not then check for a faulty bulb. The other side of the circuit shows bat power.
Thanks for the update. There is a company that rebuilds those clusters for a fraction of that cost.
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