Troubleshooting guide for electical?

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Texan

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I am looking for a troubleshooting guide for an electrical problem on my 2000 expedition. When the key is turned to the ignition on position the interior of the truck loses power to the ODBC connector so I am not able to download any ODBC codes. Here is a little history:

I went out to start the truck, it turned over a couple of times but did not start. I jumped it, same problem. I measured 10 volts at the battery. The battery was 10 years old (a kirkland) so I went out and bought a Interstate new battery at coscto. Installed the batery. This is where things started to go crazy ...

When I turned the key, the instrument gauges were moving all over the place, relays clicking under the dash, lights going on and off. Crazy. I tried to start the engine anyway but no joy. I tried turning the ignition on and off with varying levels of insanity from the the dash, interior lights and relays. It seems that with each attempt different items just stopped working.

Current status: If I disconnect the battery for 30 minutes, then reconnect the battery, then the under hood light comes on and the interior lights come on. I also see power at the ODBC connector. Insert the key, if the door is open then the key in/door open warning chime sounds. If I turn the key to ACC, then the radio comes on for a couple of seconds, then everything goes dark. No lights, no radio, no power to the ODBC port. Nothing. Take the key out and the battery saver relay starts clicking on and off. The under hood light flashes and the ODBC port goes on and off in sequence with the battery saver relay.

Another strange symptom - the door locks still work with the remote, but they go up and down as if power is pulsed at around 10 pulses per second (I have not timed them). The battery saver relay clicks at about 1 cycle every second - so they don't seem to be related.

I've checked the fusable links at the battery, checked and rechecked the battery connections, checked all the fuses. I have also examined the area around the GEM, I don't see any evidence of water intrusion. Everything looks really clean.

The engine compartment did get wet the day before all of this happened.It would make sense that there is a problem in the engine compartment that caused the battery to drain (the last straw for a 10 year old battery). The ground strap looks good.

I'm not sure where to start. I don't want to just start replacing random parts, but I can't find a troubleshooting guide for this truck. Any suggestion?

Texan
 

Bedrck47

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Have you had any rain just before these problems occurred.

Have you noticed any water on the drivers side floor?
 
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Texan

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We did have some rain, but no evidence of water on the driver side floor, and the area around the GEM looks clean and dry. I pulled the steering column collar off so that I could get a good look.

Have you had any rain just before these problems occurred.

Have you noticed any water on the drivers side floor?
 
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Texan

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Solved. The problem, not surprisingly, was corrosion on the surface of negative battery terminal (where is contacts the post). I did not properly clean the terminal when I replaced the battery. It was passing 12v at low amps, but when the truck tried to draw more amperage the voltage would drop and cause the GEM to go into a funky reset mode. I miss the day when a problem like this just caused the lights to dim.

Oh, by the way ... I started the truck, let it idle for a bit and 3 minutes later it stopped. Out of gas. Argh. This is not my best day.
 
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