9 replies to this topic

[80sMiniCity]

Hi,

I’m checking the brown wire that runs from the starter solenoid to the fuse box (#2 fuse) and get a 12 volt reading. This is the fuse that gets power when the ignition is off. As soon as I put a load (test bulb) on it I get 0 volts and the bulb doesn’t light up.

Does this sound familiar…I get the hazards working and the indicators stop. Fix both of them and the headlights stop working. Get the headlights to work and the hazards stop again. I think it’s time for a new harness.

Thanks

[lrostoke]

Sounds like dirty connections, try cleaning up the earths, and also the connections where it fits to the fuse box and solenoid.

also check for corrosion under the fuse box which may be making a bad contact

[Ethel]

You're not using the bulb & voltmeter in series? - just to eliminate it, I've done dafter things

The head light / hazard malarky might be an earthing issue. The headlights can act as an earth if the earth they share with the other lights is duff - when you turn the headlights on you send voltage down the wires head on with the current from anything that using them as a route to earth 12v > < 12v = no volts.

[jimnali]

What Irostoke said!

Are you getting the same voltage on the supply to the fuse box and the other side of the fuse? Could be bad connections on either side of the fuse box or the holder not making a good connection with the fuse. I have found fuses that appeared sound but in fact had an internal fault so that it diod not complete the circuit.

Stupid question - I assume that you when using a test bulb you are connbecting it to a good earth on the body?

[80sMiniCity]

What Irostoke said!

Are you getting the same voltage on the supply to the fuse box and the other side of the fuse? Could be bad connections on either side of the fuse box or the holder not making a good connection with the fuse. I have found fuses that appeared sound but in fact had an internal fault so that it diod not complete the circuit.

Stupid question - I assume that you when using a test bulb you are connbecting it to a good earth on the body?

When I check the voltage at the fuse box I remove the fuse and check the voltage on the hot side, which is 12 volts. I hook up a test bulb to the hot side; the bulb is grounded to the engine ground strap. The bulb does not light.

With the fuse in place I get 12 volts on both sides of the fuse, but 0 volts with a load (lights turned on), and no lights.

I cleaned the connections at both ends of the brown wire and still have the same issue.

[jimnali]

The headlamps and indicators are on different circuits so it is likely that you have two separate faults. The only places they come together are where they take their power from the solenoid and the earths to the body. I suggest that you take the connectors off the solenoid (disconnect the battery first!) clean them up and re-assemble. While you are at it, make sure that the battery connections are clean and are screwed firmly in place.

Don't rush to buy a new loom - they cost around £200 and require a lot of work to fit. Invest in a soldering iron, a crimping tool and a supply of bullet and baynot connectors. Work you way around the car replacing all of the connectors - this will resolve most of the electrical faults and make your car much more reliable.

[jimnali]

Hmmm. Assuming that the test lamp does actually work, have you used it to test the other connections to the fuse box? Have you used the test lamp on the brown wire at the solenoiod? If it works there then there has to be a break in the wire1
.
Fuse #2 is for the horn and headlamp flashers so is separate from the headlamps and from the side lights (fuse #4)
Can the electrics cope with a significant drain - eg headlamps or starter?

[tiger99]

I second not fitting a new harness. This is only dirt and corrosion, maybe even fracture, at a few of the terminals, probably mostly on the fuse box. Clean the lot, and think about a new fuse box. (If you can, fit blade type, the contacts are very much more reliable, but note that the fuse ratings are specified differently.) You may also want to check that all the terminals are correctly fitted. It is possible to push one on, with the blade going between the metal and PVC sleeve instead of under the two folded-over edges of the metal in the female, and it results in a remarkably poor contact, although the wire may seem to stay in place.

If you have voltage on the brown wire, with no load, and the voltage collapses under load, there is very clearly a high resistance at one or more places in the circuit. That involves EVERYTHING from the battery earth connection to the body, battery terminals (if they are pot type, throw them away and fit clamp type, as they will fail sooner or later), battery, the main battery feed cable, the connection from the brown feeds to the battery feed at the starter solenoid terminal, and depending where you are earthing your test lamp, possibly also the engine earth strap. Check that the voltage stays up at 12V at the main battery feed at the solenoid terminal, to prove that it is not at the battery etc.

The fault is between where the voltage is consistent and where it drops, and you should be able to narrow that down to one piece of wire, or even one terminal.

I have seen situations on several cars, not all Minis, where a multimeter or even test lamp would show 12V, and it would collapse to near zero just by applying some more load, even sidelights, and every time it was a pot type battery terminal.

If it is not that, examine the ends of your brown wires very carefully, for fracture or corrosion right at the terminals. If there is sufficient length, fit new terminals, but do not be tempted to use a cheap, nasty crimp tool, such as you will find in Halfords etc, as you will only multiply your problems later. Safer to solder.

If all else fails, just run in some replacement brown wires of the correct gauge, and tape them to the existing loom.

[80sMiniCity]

I replaced the connector on the brown wire from the solenoid at the fuse side. Didn’t have any 3/8 connectors for the solenoid side. That seemed to work. It must have been a bad connector to the fuse box.

I did a very bad thing…I opened the hazard switch when I moved on to the indicator problem. Now I get to spend the day figuring how to get it back together, or wait a week to get one over here in America.

[tiger99]

Good, well done, one problem fixed, and the fault was in one of the likely places.

But you have been very naughty! Most car switches don't seem to work again once they have been dismantled. I think they are assembled by machines which do what is not possible with human fingers.