Question about 2002 Nissan Altima
Getting U1001 and P0420 codes, car is also having electrical problems when turning on AC wipers stop working or intermittent and headlights go on and off really fast....relays clicking really fast as well... Any ideas....thanks a lot.
U1001 indicates that the ECM either isn't, or at some point in time wasn't, in communication with other controller modules on the car. From the sounds of it, I would suspect the BCM. Check the wiring harnesses at both of those places. If they are fine, you're probably going to have to replace the ECM, or spend some time looking for a short "somewhere" in the vehicle wiring, which can be a long and painful experience and would probably be wasted time in this case.
Posted on Jul 14, 2013
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Posted on Jan 02, 2017
You did say, "Any Input", right?
I had this problem with a 1992 Pontaic Bonneville.
Customer brought it in, and after days of diagnosing it drove me crazy. Turned out to be the wiring harness that goes from the camshaft sensor, and crankshaft sensor to the coil pack, had breaks in the wiring.
Everything checked out with a multimeter. All sensors, and related hardware checked out. Seems this wiring harness is doomed to fail after time goes by, because of the location. It's behind the water pump on this V6, 3.8 Liter transverse engine.
NO, I didn't replace it with a GM part! I made my own, and KNOW it will last now!
Such a JOY to get to! I put myself to sleep at night thinking about how much Fun(?) that was!
Posted on Jul 18, 2009
sounds like you have a short or perhaps a bad ground wire. Can you check the current at the relay socket? That would tell you if the short is after the relay or before it.
Posted on Sep 22, 2010
You really need to verify a good clean ground for each headlight - it is possible you have corrosion either on the end connections or in the middle of the wire. It may be a good idea to just replace each ground wire for the respective light. Splice into the existing ground and run it to a new location, ensuring there is no paint or rust in your connection and putting dielectric greaseon the wire end,terminal, and underside of the head of your fastener. The cut the old wire so that fault cannot cause issues with your new ground. Don't wrap your new wire around a bolt - use the proper gauge eyelet terminal. If you use a pre - existing ground ( like on the alternator bracket ) wire brush the bolt head underside and mounting area clean along with whatever eyelet terminal there, grease all sides using fresh dielectric grease and tighten bolt securely.
This should cure your problem - if not, then test ( and replace if necessary ) whatever headlight relay (s ) you have - they may overheat and short out, causing a power surge that would blow the bulb.
Posted on Nov 20, 2010
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