Electrical issues with dash (fuel gauge & shift indicator)

JEAkerman · May 7, 2019

Hey everyone, so this has been an on-going battle for a few weeks now and I am at a stand-still. Driving a 2002 Sierra 1500 4x4 5.3L ext cab.

This is all started with a power draw coming from a mystery location, the battery wouldn’t hold a charge for more than a couple weeks before being drained and needing a boost every time you started it. I replaced the battery twice, no luck. The last couple times it was dying I would lose rpm and all the electrical would flash, i’d Let off the gas and it would figure itself out. Won’t start the next time without a boost.

Last time I replaced the battery with a new, the truck began to fail again, this time the security light came on, lost the fuel gauge, and the line under the shift indicator.

Taking a more proactive approach, again replaced the battery (got to love warranties), took the multi meter and began checking. Started with the alternator and noticed AC voltage, replaced alternator (it was squeaky anyways). Then did a parasitic battery draw test, went through all fuses and everything was within spec. All fuses were good and cycled all relays as well. Cleaned all the grounds that could be reached and found.

With the new battery and alternator, the truck starts and runs well, and doesn’t seem to have the parasitic draw. Tried to hook up the OBD2 reader and continue to get a ‘link error’ truck will not communicate with reader but have continuity with all the pins. Tested the reader on another tuck and worked perfectly. Moving to the lack of lighting, security light flashing, and lack of fuel gauge, moved to the ignition switch. Thought something might be wrong with it because we lost the PRND123, odometer, dash backlight, and all climate controls. But when jumping between 2 upper contacts on the ignition switch, all worked other than the shift indicator line and gas gauge (again). Replaced the ignition switch... didn’t help at all, same problems and the same result with jumping the upper contacts. My head hurts haha please help.