Chrysler Repair: fuel gauge always reads full: 00 Sebring convt, chrysler sebring convertible, chrysler sebring

Question
I have a 2000 chrysler sebring convertible that the fuel gauge always reads full on. I pulled the unit from the tank and can see no visible problems. The float moves freely. I also unplugged the wiring harness to the tank unit and turned in the key. The gauge still goes to full on the instrument cluster. Is the unit in the dash bad?

Answer
Hi Greg,
The gauge float operates a variable resistor which would appear to me to be arranged such that when the tank is full it shows a low resistance to ground and when the tank is empty it show a high resistance to ground. The resistance is sensed by the body contrul module by a dark blue wire that comes from the tank and goes to pin 15 of the 20-pin black plug at the body module and then digitized and sent to the cluster. I would take a look at the resistance to ground that is shown on that wire either at the tank or at the pin on the plug of the module. It it reads 0 or very low ohms when there is low fuel level in the tank then the dark blue wire is shorted to the chassis due to a break in the wire's insulation and you need to find where it is broken. If it shows a moderate resistance and it varies smoothly and as the tank is increaingly full it drops in resistance, then that would be normal and the problem is probably in the cluster circuitry.
The body control module is under the dash at the driver side end and is attached to the back side of the fuse block that you see when you remove the end cap of the dash. I am not certain whether you can access the plug without removing the combo unit, but take a look under the dash where there are a number of plugs for the combo. There is only one black plug with 20 pins. If you have to remove it then you have to remove the center bezel, instrument cluster hood, and underdash silencer panel, pull the plugs from the fuse block, then the 3 screws that hold it in place and pull straight down.
Roland
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