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BMW e30 electrics - 2 questions

HI, I recently bought an e30 touring 320i, and have a couple of electrical problems to sort.

  1. My rear wiper doesn't work (washer does) and I'm a dunce at auto electrics. How do I test whether there's power getting to the motor?

I'm thinking a very long circuit tester cable connected to the power cable at the wiper motor end (whichever it is) and then connected somewhere at the front end of the car - where tho????

  1. I inherited a car with 1 speaker out of 4 working and the two speaker cables that emerge at the rear of the car not traceable to anywhere near the head unit, so I'm thinking I need to put in new cable. My question is what's the best route from front to back of car on an e30 for cables?

I'm thinking along the sides under carpet and trim strips, but how do the latter come off???

TIA

VZ

Reply to
Vasili.Zaitsev1943
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Just get a £4.99 multimeter, put it on the volts setting, switch rearwipe on and see if it reads a voltage (black meter lead to clear metal on car body, red lead to any wire going into motor until you get a reading of 12-ish volts.

Join the loose ends of the speaker wires together (creating a loop), then go to the head end and with the multimeter on the ohms or continuity setting try to get a reading. You aim being to identify the wires you joined together and so know where they originate from.

Reply to
Graham

Thanks Graham. I'm pretty certain there's no power getting to the motor. I wanted to try and identify where the break in the circuit might be so wanted to do a continuity check from the bonnet end of the car

cheers

VZ

Reply to
Vasili.Zaitsev1943

Vasili.Zaitsev1943 ( snipped-for-privacy@googlemail.com) gurgled happily, sounding much like they were saying:

There'll almost certainly be two wires going to the wiper motor. One ignition live, for the parking, and one switched live to set the motor going.

When the switched wire is live, the motor turns. When that wire ceases to be live (the switch has just been turned off), the motor continues to turn (on power supplied by the ignition live) until it reaches it's park point. If the ignition is turned off, the motor will stop instantly.

So you want to find a good earth, and identify which of the two wires is the ignition live - +12v all the time the ignition is on. Then check to see if you've got +12v to the other wire when the switch is on. If you've not got +12v to the switch wire, try supplying +12v from the igntion feed to that pin on the motor. It should turn.

Reply to
Adrian

Thanks for that. I seem to have 4 wires going into the motor, but I'll give em a try. I've just tried connecting a 12v motorbike battery to earth and touched the other end on all four conns into the motor in turn and got nothing. I'll also try and also do a definitive test on the cabling going in soon.

Reply to
Vasili.Zaitsev1943

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