[b]Help, electrical problem[/b]

Post by **246gts** » Fri Oct 28, 2005 11:23 pm

Just followed AA truck back from centre of Manchester with my daughter Julia's Moggie on board. She came out started car ok radio going on and off, drove about three miles then suddenly everything failed, lights, ignition etc. I arrived expecting a fuse problem but fuses ok checked with meter there is 12.48v at each side of the fuse other fuse seems ok, the re is also a fuse on two wires coming out of loom just below fuse box this is a 35 amp and although it shows signs of being hot it is still intact and takes current.

I disconnected radio from fuse box in case that was problem. Strange thing is horn works, interior light works but otherwise no side lights, no ignition, no wipers. Checked back of ignition switch and wires appear ok. ANY IDEAS PLEASE??????
Dave

Post by **TerryG** » Fri Oct 28, 2005 11:41 pm

Have you checked all the leads going to the solonoid are on tight and the contacts are clean?

Post by **246gts** » Fri Oct 28, 2005 11:44 pm

Had a quick check at side of road and yes everything seemed clean and intact. Do you think it could be the earthing strap?
Dave

Post by **Packedup** » Fri Oct 28, 2005 11:46 pm

Horn and interior light - Ignition independant, brown into fuse box, purple out (I think)
Wipers are on the ignition dependent fused circuit, white in green out on the fusebox. I can't remember if the lighting system is fused, but I have a feeling it isn't.

I don't have a Minor wiring diagram to hand right now, and though I should know all of this (having been wiring up the pickup recently) I can't remember it well enough

However, have you got a good connection on the battery terminals? It's possible for them to be loose or dirty, so you'll get low current - Your meter will see 12 volts, but the moment any serious load is put on the system the connection fails. Check the solenoid terminals where the main pos goes to.

After that I'm at a loss, you've got battery power to the loom if the interior light and horn work, but you're not getting any lights (not ign dependent) or anything on the ignition circuit. Voltage regulator? I'm trying to remember what colour the main light feed is, blue and brown? Which I think appears on the regulator (end terminal nearest the wing), which is why I'm wondering if it's something to do with that.

Wish I had a diagram here!

Post by **TerryG** » Fri Oct 28, 2005 11:53 pm

Each lamp cluster is individually earthed so I doubt there is a problem with all the earths. Even if the battery terminals are very dodgy the lights should at least come on (however dimly) All I can think of is a dirty connection on either the fuse box, regulator, or solenoid. There are lots of people on here with LOADS more experience so somebody may have another suggestion but I find most minor electrical problems can be remedied by wiggling all the wires or pulling them off one at a time and checking they are clean and tight.

Post by **Packedup** » Fri Oct 28, 2005 11:58 pm

Am I right in thinking the live to the ignition, and the live to the light switch, aren't fused? And they're the 2 circuits that aren't working. Do they trace back to a common ancestor seperate to the fused always live part of the loom?

Post by **Packedup** » Sat Oct 29, 2005 12:04 am

Just found a diagram online - There's no key for it but it'll do

http://poachedegg.mysite.wanadoo-member ... /wires.gif

Brown and blue (NU) comes from the regulator to the ignition and light switches, and that's what you're not getting I reckon. Either a poor connection on the regulator (likely), or maybe a duff regulator (unlikely).

Post by **246gts** » Sat Oct 29, 2005 12:10 am

ou are right horn and interior light on brown into and purple out of fuse box.Lighting circuit is fed from brown and blue from control box.Brown from starter solenoid feeds via control box via brown and blue to ignition switch and then onto the fuse box through the ignition switch. I think I need to get a good look at the ignition switch in the daylight tomorrow. Two things point me to this a) the ignition switch undid itself and fell through dash a few weeks back and secondly I fitted a radio a couple of weeks back and maybe I dislodged a wire.
Maybe!!!

Post by **Pyoor_Kate** » Sat Oct 29, 2005 8:31 am

The other thing to check is that the individual wires coming off the fuse box have power - although there might be power on one or other of them, if the contact is really dirty you may find you've not got power at all on some of them.

I've had that before...

Post by **TerryG** » Sat Oct 29, 2005 9:57 am

The usual cause of electrical problems for me is the water that runs down behind the regulator turns the copper contacts green and fuzzy so they dont work at all

Nothing that a quick bit of sandpapering and some pliers cant sort though

Post by **246gts** » Sat Oct 29, 2005 1:43 pm

I think I have narrowed the problem down to the brown/blue wire going from control box to lighting switch, the plastic shrouds over the spade connectors have signs of melting. Then I took the control box off to have a look around the back and the alloy connection from the blue brown terminal appears to have corroded through leaving a bridge across which contact may or may not be made.
Looks like I now need a new control box (Sat afternoon in Cheshire any ideas??) and then rewire the connection to the lighting switch.
Does anyone haveany idea what the voltage on the brown blue wire should read?
Thanks
Dave

Post by **Packedup** » Sat Oct 29, 2005 3:40 pm

I'd expect the brown/ blue to run pretty much battery voltage as it feed the ignition, fuel pump, heater, in fact pretty much everything!

If you need to do a quick fix and you're sure it's corrosion related failure, then maybe you could run a feed from the battery (or solenoid) to the blue/ bown feeds for lighting and ignition (I'm not sure why the brown and brown/ blue are seperate on the box, or I'd suggest just sticking them together) ? A bodge, but if the car needs to be back on the road before you can get hold of a regulator...

Post by **246gts** » Sat Oct 29, 2005 4:56 pm

Some Progress!!
I found a voltage regulator in an old box of bits from my Sprite rebuild and the connections in the back are ok. So i have rewired the brown blue from the voltage regulator to the light switch which showed signs of being warm, I've put in a different light switch from my box of bits since the old light switch would not work on side lights only, maybe that was the cause of the trouble if it ws faulty, and then I checked the ignition circuit and the light circuit independently and both ok. I have just started the car and lights work engine runs etc but now ignition light does not go out until I rev engine a lot. Could this be that the voltage regulator is set up for a different car?? Perhaps after reading workshop manual I can adjust this, any thoughts?
Thanks for everyones help in this operation it is good to just exchange thoughts before trying things and setting fire to car
Dave

Post by **Packedup** » Sat Oct 29, 2005 5:23 pm

If everything is now working, and there's no shorts, then excellent

Yep, ign warning light not going out till you get a few revs is because the regulator isn't regulating the dynamo into putting out enough joice at low revs. A good clean (or maybe just a tap from what I've read here) might sort it if it's been sat oxidising away for a while, or if you have a voltmeter and bit of patience you might be able to adjust it. Check the contacts all look OK, if not then maybe get a very fine file between them and see if that helps.

I had to clean one up and adjust it to get it right for the pickup, I think I've finally managed to get it around right (just over 12v at tickover, 14v at anything much above right to the red line) but it did take some tinkering and guesswork.