I've got a 1984 VW T25 (T3) camper van and have been doing some repairs but have now got serious problems with the battery discharging. |'ve got the dash off and presumably I've got an earth problem. but am having trouble tracking it down. I've taken all the fuses out and and there's no resistance between the negative and positive of the leads that go to the battery (with the battery disconected). Presumably thats not right.
Anyone out there with an idea how I solve this problem.?
Ta
Johnnie
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johnniepotter
Ok, I will try to help.
First off I will assume that your battery is in good condition as well as your charging system. If you are unsure have a charging and load test performed before proceeding any further.
If all else checked out there you have a "current draw" issue. You are on the right track by pulling fuses. However I am unsure if your measuring technique "no resistance between positive and negative" is appropriate or accurate. You are looking for current draw...not resistance.
Here is the correct way. Using a DMM (do not bother with any "clamp on" type ammeters as you are looking for millamp draw and these are designed to pick up higher currents) set the meter first to high current setting to be safe. Most DMM's will have a high current jack to plug in the probe...typically for up to 10 amps. Disconnect one of the battery cables..+ or - does not matter. Place the probes in series (one to the battery post and one on the disconnected cable) and this will give you an accurate reading of the total current draw of the electrical system. If you get no reading you will now place the meter to a lower amp setting and start from there, you may need to use a different jack depending on the meter so be aware of this. Remember...the meter does not lie..just make sure of course that the meter itself is operating properly and used properly for measuring CURRENT. This is foolproof if done right.
Make sure the doors are closed...key is off...basically let the meter read what is happeneing while the camper is in an off and parked state.
The readings you need is as follows. 7 to 10 milliamps is normal. Up to 20 milliamps is acceptable. Anything greater then that is suspect. If you read in the 150ma area it is probably a stuck relay. However..if the reading is more then 20ma you will then need to pull fuses one at a time until it drops to a normal reading. The fuse that causes the reading to drop when pulled is the suspect circuit. If pulling all the fuses does not drop the reading you will need to locate everything connected to the battery itself including the starter solinoid..and anything that might be connected before the fuse panel(s) such as at the ignition harness where most aftermarket installations grab main power.
Don't forget to check all the simple possibilities such as a light stuck on somewhere like the glove box etc.
Post back what you find and I hope this helps. Take care.
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Thanks. Sounds like good advice. I'll try it next saturday as I don't fancy doing it in the dark.
Johnnie
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johnniepotter