2005 Navigator Electrical Nightmare
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Joined: Jun 2018
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I've been looking for an intermittent problem with my 2006 Navigator going into limp mode for 1.5 yrs. May go months without happening and then speedo goes to 0, trans stops shifting, check engine on, odometer error. Stop vehicle, wait a few minutes, read code, reset code and most times it is fine. Then started happening right after car wash and would go on for several minutes after multiple code resets. Figured it was electrical related. Found the wiring harness from the PCM going down the firewall laying against the exhaust manifold burning through the insulation.. Thank goodness someone had found the same issue. Had several shops looking for the issue but it wouldn't happen when they had it and I certainly couldn't drive it in limp to the shop.
New User
Joined: Jan 2019
Posts: 1
Likes: 0
I've been looking for an intermittent problem with my 2006 Navigator going into limp mode for 1.5 yrs. May go months without happening and then speedo goes to 0, trans stops shifting, check engine on, odometer error. Stop vehicle, wait a few minutes, read code, reset code and most times it is fine. Then started happening right after car wash and would go on for several minutes after multiple code resets. Figured it was electrical related. Found the wiring harness from the PCM going down the firewall laying against the exhaust manifold burning through the insulation.. Thank goodness someone had found the same issue. Had several shops looking for the issue but it wouldn't happen when they had it and I certainly couldn't drive it in limp to the shop.
Signed up to give big thanks to you guys for updating the thread with your harness issues. I have an 05 Navi that just turned over 250k. For a couple years it's occasionally went into limp mode after a several hour long rain storm. A month ago a car wash with an underbody blast triggered limp mode, and then all hell broke loose in the following days with the pcm throwing aabunch of network communication codes, Speedo freaking out, constant limp mode / trans acting funny. I considered throwing in the towel because it seemed like it was going very hard to track down the problem. It's also thrown a shorted out O2 sensor code for a few years which I ignored assuming it was a bad sensor which makes sense.
Saw this thread, checked underneath, and low and behold the harness in that exact location was completely trashed from the exhaust. I can't believe it ran like this so long. Cut out the section, soldered in a new section of wires, reinstalled, and runs good as new again!
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