Expert: Roland Finston - 11/11/2011

Question
QUESTION: Etax Relay Clicking.
These are the codes I am getting
u110c
p0645
p0627
u1120
u0141
u1403
u110E
p0571
u1113
WHAT IN THE WORLD? please help.

ANSWER: Hi Mark,
I don't have a manual for a vehicle so recent as your Aspen (my latest is for the '06 model year vehicles). From what I can tell by looking at those codes, some of which weren't shown in the '06 manuals, the common thread seems to one of a failure of the communication system (digital data) which along with the clicking of the etax relay makes me think first that there must be a short circuit that is dragging down the voltage on the system overall and the data bus too. So compare what the battery voltage shows when the cables are disconnected vs when they are connected and the ignition switch in the run position. If the voltage drops significantly then I would start removing fuses from the power distribution box, one at a time, and see if you can find one that eliminates the drop of voltage. You might also disconnect the alternator main battery wire and the then the field wires as a separate test to see if that might be the cause. There are so many codes there would appear to be a 'common cause' which I suspect it s short circuit. Any relevant history of this problem?
Roland

---------- FOLLOW-UP ----------

QUESTION: No I just bought the Car.
I took it in to the dealer they said they didnt hear a clicking and when they ran diagnostics they said a bunch of codes came up but they said they seemed to be old codes that probably came up before and were fixed. So they cleared it out they said and if I had problems to come back and they would re check it. But I turned my ignition on off on off on and these codes came up.
The check engine light might come on one day and I hear the clicking then. The next day It will stop. Non of the above is affecting the drive of the car

Answer
Hi Mark,
You would need to do the measurements when the relay is clicking which is diagnostic of the voltage on the relay activation being too low to keep the relay points closed, and then when it opens the short circuit that is caused when the relay closes is removed, then the voltage recovers, etc., etc. I would wonder if one of oxygen sensors is shorting its 12v wire to ground, for example, and that is usually connected to the autoshutdown relay which may also be clicking. But that is just one of many possible shorts. I am surprised that this isn't affecting driving the vehicle, unless it hasn't occured when you are driving. So you may just have to wait it out till it does affect the functioning and then do the analysis.
Roland