Car won't fire up

[SuperRedMR2]

Iv got a major problem in my loom somewhere. A positive is touching a negative and has completely killed my car. Its in the engine loom somewhere but instead of trying to find the issue im calling upon my fellow imocers to help me out and sell me a proven wiring loom for a mk1b????

Ive also got to replace the water pump i bought new as its wrong...the pulley sits far too forward so it doesnt line up straight with the crank or alternator.

The only good thing from today came in the fact that when the engine cranked before it died, there was no banging or crashing of valves or pistons.

[michaeljapp]

If you know the short is in the engine loom, can't you just test the continuity at the connector?

[SuperRedMR2]

Im not electrically minded but my mechanic was doing the testing for continuity, he thinks there is an issue coming from the fan side.

The fan kicked in straight away when the ignition went on for some reason, even when we pulled the connector out it was still going flat out.

But when we disconnected this part of the loom, there was still an issue and the car remained dead.

[Ben]

Could it be anything to do with an immobiliser? If I turn my ignition on without deactivating the immob, the fans go on flat out

[SuperRedMR2]

Not got one mate

[mk1 dal]

what fan is running rad , engine

[PW@Woodsport]

Surely if the loom was working perfectly before you stripped everything down, and it's shorting to ground now..... then that can only mean you have connected something up incorrectly?

I don't see how a new engine harness is going to solve that when it's user error?

Just find out where you messed up and correct it, i don't think the loom developed a fault when it was off the car.

[SuperRedMR2]

Nothing has been connected up wrong.

The engine bay fan was running constantly Gary.

[kaiowas]

Is the fan running your only problem? Is the temperature sensor for the fan plugged in?

If the sensor is not plugged in the fan will run (the sensor is the one on the bracket near to the lifting hook on the cabin side of the head). Due to it's exposed position it's also really easy to damage the end of this sensor when getting the engine in/out of the car so it's worth inspecting it closely and trying another if you have one.

[SuperRedMR2]

Hiya,

The connector was plugged in and it was running as soon as the key was turned. Thought it was a bit odd.

We did a continuity check when we disconnected the connector for the fan but the car was still dead when we reconnected the battery so there must be a fault elsewhere.

[PW@Woodsport]

Nothing has been connected up wrong.

The engine bay fan was running constantly Gary.

That doesn't make sense Alex, you will agree your old engine had no electrical fault at all before taking the engine out?

Since then the only thing that has happened is you, to be blunt, that is user error, you've shorted something to ground or caused the fault itself, it is impossible for a wiring loom to just develop a fault sitting on the bench.

You probably don't want to hear that but it is something you have done incorrectly, retrace everything you did and it will become clear..... for example trying to crank the engine without adequate gearbox earthing will cause a loom melt or something else like a throttle cable will then act as a ground, seen it a hundred times.

[SuperRedMR2]

I don't mind admitting when I've done something wrong, but to my knowledge so far i'm unaware that I have.

The throttle cable wasn't actually connected up but all the earths were on.

What would cause the engine bay fan to be on constantly?

[PW@Woodsport]

The engine bay fan will be on if the temp sensor on the end of the head is left open circuit, unplugged, or faulty.

I would ignore your fan being on, that is not connected to your other issues, that is simply the fan relay switching it on due to the temp sensor being open circuit.

I know you say you haven't done anything wrong, but that can be the only explanation, if you concede you had a fully working harness before engine removal, and all it has done is sit on the bench, then refitted, and it has problems now.... then the only variable in that is the fitter.

In short you've done something wrong, if you got a fresh loom and connect it the same way you will have the same problem, just retrace everything you have done, inspect alternator wiring in particular, starter main terminal too... if any of those are shorting to ground you will get your problems.

[elbon50]

Seem to remember you said you saw a spark when you connected the battery Alex

There are some hidden fusible links in the engine loom

One is on the ignition circuit I think

Wondering if you may have accidentally blown a link

[SuperRedMR2]

That was because the alternator casing was touching the bodywork and none of the ignition sensors had been connected at that time.

I only connected the battery so I could do my windows up.

[jimi]

There are some hidden fusible links in the engine loom

There's only one and it's here

Edit
If the fusible link is blown you will get nothing, no lights, no ignition, the car will be dead. The only part of the electrical circuit that doesn't go through that link is the main power feed to the starter motor.

[SuperRedMR2]

Mine is completely dead...

[jimi]

It's easy to check, just cut the tape and slide the black woven sleeving out the way, the link is a section of special wire soldered in, if it's blown you'll see it. If it is blown the question you have to answer is why did it blow? it normally takes a dead short to blow it.

[elbon50]

Mine is completely dead...

Completely dead but I remember you saying that the engine bay fan was running

Presumably that wouldn't be live if the link had blown

What think you Jimi ?

[jimi]

If the fusible link is blown you will get nothing, no lights, no ignition, the car will be dead. The only part of the electrical circuit that doesn't go through that link is the main power feed to the starter motor.

As I said nothing will work