truck is 2004 standard cab Dakota with 3.7 5 speed rwd. 2 weeks ago i goty into the truck to go home , started fine , ran fine, put truck into gear, released brake, turned on lights because it was raining, then i heard the bell in the dash chime like it soes when low on fuel. i looked down , no idiot lights on so i kept going . as i merged onto the interstae i lookeed down and saw i had no guages. 2 times while moving it chimed and the guages tried to move. i got home , checked the mail and realized i had no marker or tail lights, only headlights. parked truck went in to house, came back out , checked all fuses and relays , all good. started back up, guages were fine...until i turned lights on . lost it all again . disconnected battery, cleaned cables and terminals, removed ground cable from fender, cleaned and reassembled. no change. put an identicla body control in and still no change. does anyone ourt there have any ideas where i can go next ?

 

The first rule of troubleshooting is, what has changed? You have everything working, then you make a change when you turn on the light switch. After you turn on the light switch, you lose everything. My guess is you have a short in the light switch, or somewhere along that circuit. When you shut the truck down, it kills power, and whatever you're shorting goes back to open. I think I'd try replacing the headlight switch. If that doesn't work, start checking the wiring along the headlight switch wiring path for any damaged wiring. The gauge lighting is also controlled by the headlight switch via the thumbwheel **** to the side. Good luck, electrical issues are a major pain. Hope this helps.

 

The headlight switch sense circuit, it doesn't actually turn the lights on the CTM does, and the cluster all share the same ground, G208. It's located behind the left hand kickpanel. If you follow the wiring from connector C1 on the CTM down it should lead you to it.

 

have you checked the voltage on the battery. As stupid as it may sound, I had an alternator go out on an old car and when it was dying strange things happened with the electrical including gauges not working occasionally

 

Ok. . Checked all grounds , they good. Headlight switch was replaced , battery is steady @ 12 volts . I am guessing the body control is at fault and the one I swapped is also defective.

 

body contrl module has no effect or correlation to gauges that I know of

 

If the battery is good, it will read 13.2 or thereabouts. If it's only showing 12V, it's getting weak and may be a sign that the alternator is not charging. Check the battery when it's been sitting for a while. Any parts store can check both the alternator and the battery. If one is bad, I suggest replacing both.

A low battery may also be a sign that you have a short in the system, which goes along with what you're having a problem with. Since nothing else has worked, you may just have to bite the bullet and start tracing the wiring for the affected systems, paying close attention to anywhere the affected systems share a harness or where they cross parts they can rub against. Good luck, tracing a wiring problem is one of the hardest jobs there is on a vehicle.

 

Battery reads steady 12v after sitting all this rime. Running it shows 13.9 v

 

Still a bad battery, and it's going to take your alternator with it if it hasn't already. 12V is 1.2V short, and alternators are set to produce anywhere from 13.5V to 14.2V. An alternator has to produce more voltage than the battery in order to charge it, and when you measure it engine running the alternator's output will make the battery appear to have 13.9V. An alternator that has to constantly charge a bad battery will eventually smoke the diodes, and then the alternator is dead. It can turn into a vicious cycle, battery dies, kills alternator, battery is replaced, dead alternator doesn't charge, kills battery, alternator is replaced, alternator dies trying to charge dead battery, ect ect. In the meantime, your truck does funny stuff due to low voltage. And, the newer the car, the more important having a steady, reliable voltage becomes.