QuestionQUESTION: I have a 2000 cirrus with a fuel gauge problem similar to the one mentioned in an email you received back in 2008. I already replaced fuel pump and sensor unit in the tank that worked for a day or 2 and the gauge started jump around. You said there is control module that can also go bad. Could you provide me with more information on how to test it.
ANSWER: Hi Bob,
If you could mention a date for that earlier q and a that would help refresh me.
The fuel level sensor is connected on a dark blue wire from pin 2 at the fuel pump module to pin 15 of the 20-pin black plug of the body control module which is located under the dash on the back side of the fuse box that is mounted behind the left end cap of the dash. You have to do a bit of disassembly to get to it. In the bcm the signal is digitized and sent with many other signals on a common twisted wire bus to the instrument cluster. So either the wire from the sendor to the bcm plug is flaky, or the bcm is not digitizing properly, of the instrument cluster is not reading the digital signal reliably to operate the gauge. I don't know for sure which is the problem and except for checking the voltage signal to be solid or flaky at pin 15 I would not know of a test to sort out the bcm from the cluster as the cause. You could try the instrument cluster self-diagnostic test by pressing on the odometer/trip reset button and then turn the key from off to run and that will start a seried of tests. (If that doesn't start the tests then turn from off to run to start and then watch after the engine starts...the manual is not crystal clear about this. But try various things but always begin by pressing and hold the reset button and then doing the ignition key variably, and releasing the button variably to get the a start of the insturment segments to test along with the warning lights). Then it should launch into Chec 1 for the gauges which in four steps will display the fuel at full, 1/2, 1/2, and E if the gauge is OK). Please let me know how you get these tests going.
Roland
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QUESTION: http://en.allexperts.com/q/Chrysler-Repair-807/2008/7/fuel-gauge-malfunction-200
My problem is the same as the question above as I mentioned in my email. My tank is now full and shows full the low fuel light is off,but I only put 6 gals in the tank. I may travel 100 miles and the problem will start with the gauge jumping around. When I replaced the fuel pump the tank wasn't empty it was about half full, would that make a difference. The float design was different on the new unit, the old one was in line with the pump on the side, the new 1 is bend at a 90 degrees to the pump on the side.
AnswerHi Bob,
I don't know about the difference in the design of the units. My suggestion would be to find the dark blue wire (either at the tank or at the body control module as there are no disconnects shown along its routing, and probe it with a pin through the insulation. See what the resistance to ground is indicating with it full, then 3/4, 1/2, 1/4, near empty. It should vary smoothly over the range. If it does, then the issue is not the sender and ideally not the wire (certainly not if you are reading at the bcm plug), and so it would likely be the cluster. If it is intermittent or varies rapidly in resistance for small changes if the fill of the tank then that would indicate that the float is not moving freely.
Roland
