Electrical Hell!

[Lephosto]

So, where to start? I know theres a short somewhere in the car because if I let it sit for about a week, it needs to be jumped. The Windshield wipers, when connected, don't turn of. And I have just had to replace the voltage regulator and now the alternator and now a fairly brand new starter is down too. Not sure if one caused the other but any advice on whats causing the damage? Or is it just bad luck!?

Ehh.... A little more detail I guess wouldn't hurt.

I had an issue with the voltage meter maxing out randomly which lead me to replace the voltage regulator. That seemed to fix the problem. I then let it sit for maybe a month and it wouldn't start. Could hear the fuel pump working but it wasn't turning over. I had an alternator in my room (Bought at the same time I got the voltage regulator) so I put it in. Took the old one to get tested and it failed. Still wouldn't start, so I shorted the solenoid and it started right up... Just figured I would replace the who starter. Am I going about this wrong? I have been replacing and finding parts that seem to be bad but am I missing the bigger picture?

[alhbln]

A defective regulator not limiting the alternators voltage might lead to damage in more "sensitive" equipment such as the radio or ignition electronics. i dont think that the starter would be affected, especially as while starting, the alternators output should be below 12 Volts. I dont know about the wiper circuit but it might have been affected by the higher voltage.

If you have replaced the alternator and regulator, and the battery is ok and charges, then some component or faulty wiring is drawing current, leading to a drained battery. To find such a fault, buy or lend a small current clamp meter with a range up to 10A, clamp it around the batteries (+) wire and check the current drain. It should be less than 0.1 ampere with everything switched off.

If the meter indicates a higher current, start by pulling the fuses one by one to isolate circuits and check the result with the meter each time. If you still see a higher current after pulling all fuses, systematically check all cables starting from the (+) connection on the battery using the clamp.

As usual, make sure the ground wire to the alternator and all ground connections are in a good condition.

[Lephosto]

I never thought of pulling the fuses one by one to figure out which one was causing the problems!! It seems so simple and yet has completely evaded me !! Thanks for idea, I will certainly do this as soon as I get the meter. Thanks a lot!

[alhbln]

BTW, if you dont have a current clamp, start by removing a fuse and use a Multimeter to measure the current between the two terminals of the fuse. Do this for all fuses to get a first impression.

[Lephosto]

What should it read when I test the fuses?

[MikeW]

It should only read a few milliamps as I recall. Really just enough to run the clock. Other fuses should read 0 if the circuit is off. An even easier first step is to check at the battery itself. First turn off all lights including the dome light. Set your multimeter for the maximum amps (10A or 20A usually) and disconnect one of the battery cables. Insert the meter in series between the cable and the battery post you just pulled it off of. This will tell you your total drain while everything should be turned off. If it's a reasonably small number then the problem is elsewhere. If not you can then check the fuses one by one as has already been mentioned.

[Lephosto]

So finally got a hold of a multimeter and I don't know much about electrical. So I went outside and began to get information from my car... unfortunately I didn't have the idea of coming back up here and checking to see what you had told me to try . Instead I did volts instead of amp across the fuses and battery. Does that work? Is there a diagram that will tell me what each fuse is for and what the fuse is supposed to be? I'm pretty sure some of the fuses in their are wrong and I tried to write down what they are and how many volts were going across them when the car was off. So I hope this helps, the first number is what I think the fuse is.... and the second was the voltage across from it. Please be patient with me, I have't worked with fuses yet so I hope I got the right info. In this order:

(Left set of fuses)

250v - .1 mV

10a 32v - .1 mV

250v - 13.9 mV

250v - 13.6 mV

20a 32v - 2.8 mV

30a 32v - 1.2 mV

250v - 2.1 mV

(Right Side)

15a 32v - 9.6 mV

250v - 20 mV

250v - 11.7 V

32 v - 18.1 mV

250 v - 12.14V

20a 32v - .5 mV

1-1/2a 32v - 0 mV

I'll go back out tomorrow to gather the information in amps. Hopefully this will help though.

Edited June 18, 2009 by Lephosto

[240dkw]

Lephosto: Remember to remove the fuse and read the amps across the two fuse holders, if you leave the fuse in there will be no amp reading, as well it looks like the third and fifth fuses on the right side are blowen, if you get a 12V reading across a fuse it is bad.

Dan

[lmcguffin]

Checking voltage across the fuse to check the fuse condition only works if there is a load on the fuse, ie: if the fuse feeds a switch that is open or off then there is no potential to create a voltage reading. The way to check a fuse without taking it out is to connect the negative or black lead to a chassis connection (preferable unpainted metal) and then use the positive lead to check both sides of the fuse. If the circuit is active then there will be voltage (12VDC) on at least one side of the fuse, and if the fuse is good then 12VDC on both sides.

Also, the z cars have some circuits that are switched upstream of the fuses, ie: headlights. So the headlights have to be on to test the circuit.

You can also remove the fuse and use the ohm scale on the meter (horseshoe or omega symbol). 0-1 ohms indicates a good fuse; open or > 100 ohms would be blown.

[Lephosto]

I had pulled out the fuses and thats when I took the readings. As to say, I pulled out the fuses one at a time and while it was out, connected the multimeter to where the fuse would be and those were the readings I got.

Edited June 18, 2009 by Lephosto

[MikeW]

Yes, but you really need to read amperage, not volts. For the most part volts will be either 0 or ~12. The millivolt readings you were getting don't really mean anything - they're basically zero. You headlights, starter, and dashboard lights all use 12 volts but pull vastly different amperage. If you read 12V that means that the circuit was active which may be fine if, for instance it was just the low draw running the clock but bad if there's a short somewhere.

[lmcguffin]

Since you are checking voltage all this will tell you is that there is a load connected, ie: dome light. Reading 12VDC means there is a load; reading mV means no load or switched off. If there is load on a circuit that should be off then this could be a culprit. This was originally about checking leakage current (amps), but that requires you to be a little more familiar with your multimeter. You can check DC current with most multimeters, however they are limited to the amount of current they can read and will typically have a rating by the A or mA jacks (10A, 400mA, etc). There is an internal fuse that protects the meter (and your circuit being tested) from overcurrent. Checking current with your meter basically makes it a fused piece of wire, so if there's a direct short then something will blow, hopefully the fuse in the meter and not the meter itself. Be careful on the circuits where you read 12VDC across the fuse as there is a load there. Or get a DC clamp-on type as they are not connected to the circuit. Here's a link to a site that has some Factory Service Manuals:

http://www.xenons30.com/reference.html

See if you can get the Body Electrical section for your year (or close). This section will have the fuse box layout, fuse sizes, and circuit schematics/wiring diagrams.