Topic

If swapping relays around has changed, or created more symptoms, then suspect the relays.

Just replace them both, using contact cleaner where they plug in.

Also worth checking ground points around the relays for good contact.

If you replace the fuse with a bulb then you will not blow any more fuses

Hi I had a bit of time and did what you said and put a bulb across the fuse and it lights up bright for about thirty seconds then goes off, but I thought I heard a noise from the fuse box took it off and now the light doesn't come on and it only flashes when the fuse is out and ignition on,it has stopped blowing fuses. But the engine cooling fan is on all the time. Also while working on it I found that the wipers have been on all the time but obviously not moving motor very hot to touch. New fuse box ?

Ok, something seriously amiss here.

Wipers are fed by fuse 19 in the fuses in the dash, and have no commonality with the fuses that are blowing, other than the fusible links in the under bonnet fusebox.


It sounds like either damage in the loom or the fusebox under the bonnet.

I would disconnect battery, then dismantle fusebox and check that, then trace through all wiring looking for a fault using multi meter rather than risk cooking anything.

Thanks I am beginning to think fuse box, but not to confuse the issue the wipers were switched on might have been by mot examiner then stopped I didn't notice as they were not working and car isn't used in rain.

If wipers were ON, but not moving, and hot, then wiper motor is jammed. They often corrode internally as water gets in and can not escape.

As this is a largish motor, if it was ON and not moving, this would have produced a large load (almost a short circuit) on the electrical system, and could have caused all sorts of symptoms as could have dropped the battery voltage, burnt out connections, damaged wiring or carbonised insulation. (A stalled DC motor can draw over 10x the amps than when it is running!!) Disconnect the wiper motor befor carrying on.

What size bulb did you use? If 12W or similar then max current would have been 1 Amp, much less than the 30 amp that was blowing the fuse but well within the load capabilities of the wiring!

**note inserting a bulb as described will NEVER burn out or damage anything that is working correctly! It just limits the maximum circuit current into the circuit.

However, as said, the 1 Amp for 30 seconds could have "burnt out" the fault causing the short circuit, which sounds like it was in the fuse box!

What is the status of the original problem now? It sounds like the short circuit blowing fuses has cleared?

Yes, wiper motor is incredibly badly designed. Mine filled with water a few years back and corroded into a solid lump.



But electrically it's nowhere near the original problem, so unless there is a short in the loom, I tend to think it's a bit of a red herring on that score, but will need fixing all the same.

Thanks for that, was unsure but thought I would post have changed the relays around and that does seem to change problems.

What is the best way to test relays please?

Well, you need to know the pin outs for each relay.

Once you know that you connect one test probe of your multi meter to the common pin and check that the normally open (NO) pin is open circuit, and the normally closed (NC) is closed circuit is makes continuity.

Then you put 12v through vthe relay coil and test again. The situations should have reversed so NC is now open and NO is now closed.

Do this a few times to make sure relay doesn't stick

Not all relays have both NO and NC, in which case you just test whichever output state there is for continuity and apply 12 across the coil and check for a state change.



But by far the easiest method is to swap the relay with one of the same type in the car. If the fault moves, then you have found the duff relay

Thanks do those Bergen relay testers work, does anybody have one ten relays between £50/100 tester £17 moved them around and problem has moved.

Thanks again well ordered relay tester checked relays all ok, so checked all fuses and only one was gone 15A under hood had gone replaced that all though it says for brake lights/horn which are working well lights as had disconnected horn but OBD was not. Used for a couple of days tried to go shops today same problem kept blowing fuse put light in to replace fuse, lights up bright for 20/30 seconds then goes off change fuse a couple of times and now car is working.