*BOTM Feb '11, Mar '12*
Join Date: Aug 2008
Location: Visalia, Ca
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So does the Tach even do the initial sweep?
Have you checked the combination meter input line?
Disconnect the combination meter line and tap the yellow/green wire and a ground with a multimeter. Start the motor and measure input peak voltage. Peak Voltage should be at 10.5V.
If peak voltage is normal, the combination meter is at fualt
If the measured value is below 10.5, replace the ECM (per Service Manual)
If the value is 0V, check for continuity between the combination meter on the black connector and the grey connector from the yellow/green terminals.
If there is no continuity, check the harness and sub harness for an open circuit.
If there is continuity, your circuit board is faulty. If it is faulty, I would see if I could but a used or even broken gauge cluster on ebay and swap the board with yours.