electrical troubleshooting

[BigDaveZJ]

Trying to figure some thing's out here so I can get back to using all my truck's features again without draining the batteries.

Anyways, last summer some electrical issues popped up. Batteries would be drained after sitting for just a couple hours, no imminent signs of what was causing the draw. During one of adventures trying to figure out what it was, I noticed that the #1 relay in the PDC under the dash was spazzing out. So I pulled it, losing my dome lights. This allowed the vehicle to start again, but one of the batteries was now toast so we replaced it.

So I finally got around to troubleshooting it a little bit more today. Put the relay back in, giving me dome lights. However the dome lights would not go off when I shut the door. This had happened on several occasions before all of this started, but a little WD-40 in the door switch and all was well for a while.

Now for why I don't believe that the door switch caused my power drain. The dome lights would not be on during the timeframe where the batteries were drained. Also, I have an alarm on the vehicle, and the alarm never went off, so the vehicle never thought the doors were open. So my theory is the door switch is a problem, but it is not the problem that lead to the battery draining.

And something that may or may not be related. Sometimes when I start the vehicle, my pyro gauge maxes out for a couple seconds and then inches back to reality. No clue is this is related or not.

So here are my theories:

1) Bad Relay - easy fix, replace relay, minimal investment lost if wrong

2) Wiring Issue somewhere - PITA fix

3) Some other things that I haven't thought of yet


I figured tomorrow I'd try throwing a new relay and door switch in there, see what happens, and go from there.

Sound like I'm on the right track? Any other ideas?

 

[no-red 6 0]

replace the other battery..

 

[BigDaveZJ]

replace the other battery..

Other battery is just fine. Vehicle starts just fine. But only when that relay is removed. I've put a brand new Optima Yellow Top from my Jeep in it's place and everything is identical.

 

[JEFF69Z28]

REPLACE RELAY

 

[VALKYRIES]

Well lets see if I can remember what all you told me. Could be battery or ies,fuzzed contacts on the relay? Have you got or can you get a fairly good multi meter? Should have 10 amp current metering abalities.( This will be fused so will be safe) One of the cells in the battery could have shorted ?If you were to have the old battery you could test the terminal voltage, there are graphs showing the condition of the battery for voltage. If the relay had fuzzed contacts? What is it ??? 30 to 87 or 86 one is normally open the other normally closed. To see if it is good? Should have > ohm or resistance if the contacts are closed and in good condition.The coil should have about 80 ohms of resistance if the coil is good.Contact #'s ???
If you have the current scale on a mutlimeter pull a fuse and put the probes on each side of the fuse sides. The current will now be going throught the meter if under 10 amps and will read what is being drawn. You can do this on any of the fuse holders maybe vary what is turned on at one time to see if the current adds up on a higher amp fuse, to what should be there? If I remember my Kerrchoff's Law? Could be a bad PCM or ECM something in it has shorted to ground? Sorry I have probably forgot some of the other things that you told us so will try again if so.