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Old 07-01-2010, 07:35 PM   #16

HeavyD's Avatar
Drives: 1SSRS RY L99
Join Date: Aug 2009
Location: Ontario
Posts: 1,329
Ok, I am a tech in the heavy truck industry. Trucks also have data links and lots of electrical gremlins. The car is under warranty, so really it is someone else's problem, but you can poke around too. The first thing you need is a complete wire diagram, without one you are wasting all your time, you need to know where to look and which wire is which in any particular connector body. Not all communication wires run in all harnesses or connectors so it is real easy to run a wild goose chase. 90% of wiring gremlins are at an actually connector body, because this is where the weak link is with the connector itself, or the terminals. I am not sure about cars, but with trucks one common problem is simply too many zip-ties. They secure the harness down with too many zip tie and the harness is pulled and stressed too much to the point where it partially disconnecting a connector or pulling a wire out of the terminal. This can happen two ways. First, the harness is tied too tight an causing stress along the length of the harness, or second, the harness is wrapped too tight too close at the end of the harness at the connector body and the outer wires of the connector body are pulled too tight. Another hard problem to find is a weak terminal. The terminal in the connector body that mate to each other are male/female friction fit. There are numerous different types of terminals, but they all make electrical contact with their mate. Sometimes they aren't formed right, mostly the female ones, where they have no friction and are loose so that when the male pin is inserted into the female pin there is little to no electrical contact. To check this you need a trained eye or a test pin to check the fit. From the sound of your problem, it is likely that you have a stressed harness somewhere. With a stressed harness one the terminals, (pins) can get partially pulled out of the body or the wire itself can get pulled right out of the pin. The only way to locate this is to wait till the code is active all the time and isolate the harnesses, or with intermittent problems, you are stuck going connector by connector. It is very rare for a newer car to have a harness rubbed through, even rarer to have a broken wire mid harness.
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