2005 Navigator AdvanceTrac Problems - Ford Forums

fitnessking · 06-30-2009, 17:13

I have a 2005 Navigator with 68,000 miles. The 4X4 Low and 4X4 High lights flash for no apparent reason at no particular time. Typically (although not always), these are followed by the Check AdvanceTrac Light. When this happens, the speedo goes dead, I have no acceleration and I must pull to the side of the road, turn off the car and restart. Everything then seems fine until the problem recurs. This is sometimes in 10 minutes or in 3 weeks. The codes when the light is on are U1900IC and U2023 VDM. This problem has stumped 2 dealers and one independent shop. Everyone seems to think there is an intermittent short, but no one knows where. This problem first cropped up in October of 2008. For what it's worth, the battery voltage and CCA are fine. One dealer looked for chafed wires at the AC lines, but they were fine too.

Any input would be greatly appreciated. Many thanks.

**360ci** · 07-01-2009, 20:31

I hate to say it, but if I remember correctly, code U2023 generally means a PCM problem. As electrical gremlins are hard to fault, when a bad one does occur, and reoccurs at any time without any said provocation then you can almost say a bad PCM. Not sure if you've had it tested or not, but I'd make sure the wiring harness is on tight (one Ford dealer here can't install fuses correctly!). If the wiring is in fact all good, then a new PCM might be your best, if not only option. The bad part is that installing a new PCM is best left to the dealer, as they have the proper equipment to legally transfer over the engine and VIN info.