Hi all. I recently installed a engine compartment complete harness to fix a open for the PCM FLD circuit to the alternator and a intermittent cruise problem, also replaced the PCM with a plug & play. now everything is working and problems are corrected but my fuel gauge goes to full when key is turned on and a few seconds later goes to empty and low fuel light comes on. did self test on cluster and checks good. seems DB wire from tank unit to cluster is open. but I have grounded the DB wire and gauge does same,also does same with DB wire unplugged,gauge worked perfect before repairs were made. need help, car is jacked up with RF & RR tires off ground and has been like this for 2 months. is it possible the cluster has to do a relearn by driving? what else could it be

 

Welcome to the site,
Sounds like the cluster test (Sweep) is working.... Now you lost back at the fuel tank sender connector (Ground or Reference)... Then you will know if it is the sender or the wiring... If you have your info back to the connector? then you know its the sender. if not, you will need to find where you broke the wire or the rats eat them. Basically saying you will need to test the wiring from the connector back up until you find the issue that needs repair. Not fun !!!! Make sure you have a wiring diagram to chase the colors.

 

I can disconnect the DB wire at the cluster and the same problem is there,I can also ground the DB wire at the cluster and it still does the same thing.. thats why Im lost. old school we could ground the wire to the tank unit and the gauge would go up

 

So you know the wires are good from the sending connector to the cluster connector?

 

Did you pull the trouble code? Should give you a (Fuel level sensor shorted or Fuel level sensor open) ?
Here you go... Hope this works...

 

yes,the circuit is closed. and I own a snap on modis,I scanned the car & the BCM and found no codes

 

Ok. Try doing the Body verification test and see if you can complete it without using a DBR-3... It may have lost its path with the replacement of a part...

 

ok.. will do this weekend.. Thanks.