2003 Ford F-150 Relay or wiring short after heavy rain

  • 2003 FORD F-150

Electrical problem
2003 Ford F150 V8 Two Wheel Drive Automatic 65000 miles

After several days of rain, I will find that the dash board equipment (lights, fan, radio, etc) are powered up w/o key being in the ignition. This will cause the battery to die if not caught quickly. I've been able to temporily disconnect the battery and re-connect and start the engine after 5-minute wait. However, after I got home and turned off the engine tonight, the dash equipment stayed powered up. So I disconnected the battery again and hope it will start again tomorrow morning. Since this has only happened twice after several days of rain, I think it's either a wiring or relay short. Any ideas?

Do you
have the same problem?
Monday, October 12th, 2009 AT 7:25 PM

1 Reply


Thanks for the info. I was able to confirm that water was in the wiring above the CJB/GEM and the connectors underneath the e-break were very wet. I removed the CJB/GEM and saw a tiny bit of water between the pins under the bolted down connectors.I used contact cleaner and air gun to clean and dry all wet connectors and wiring and reinstalled (I just want to see if CJB/GEM really need to be replaced or if being dried out again will get them working). The truck will start but strange thing continue (i.E, raido cuts off, high beams turn on/off, starter engages w/o key in ignitian). I guess my follow-up question is, can a failed CJB/GEM cause all these issues or do I have a second problem?

Good job CJB, but you forgot to mention that if you have water intrusion in the GEM then you have water in the CJB as well, which is not good cause it houses a couple of important relays (that you cant change out, without changing the CJB). What that translates into is replacing BOTH the GEM (Generic Electronic Module) and the CJB (central junction box) becuase they are connected directly to one another. The water usually drips from the windshield onto the main harness and finds it way to the CJB, then it migrates from there to the lower GEM. Before you go throwing parts at it, see if you can look at the wiring loom going in to your CJB (aka fuse panel), which is down by the E-brake on dr. Side, and see if you can get water out of it, or if it is showing signs of water being present before. If you can, then you have the aforementioned condition and need to replace BOTH the CJB and the GEM.. Ford Tech

Was this
Wednesday, October 14th, 2009 AT 9:42 PM

Please login or register to post a reply.

Recommended Guides