Short version: Land Rover does not go!
Here's the background (partly detailed in Starting problem after alternator swap, but I've now eliminated the alternator).
A couple of weeks ago I cross-connected the battery in a perfectly understandable accident which could happen to anyone. Only for a few seconds, mind, but that's all you need. Having reconnected it the right way round, surprisingly, I was able to start and run the car, and in fact drove it around for several days.
However, the stereo was blown, and the alternator light was on and the meter confirmed no charge was getting to the battery. So I got a new alternator and put it in. On trying to start the car, it turned over once but gave up, and there was just a fast clicking from the starter.
The battery was now completely flat, so I put a new one in, and tried again. All I could get was the clicking - but the battery drained quickly. With the meter I could see that when I turned the ignition to START, the battery voltage dropped to 5V. If I just turned the ignition on, without starting, I saw a slight voltage drop for a few seconds and then a click and the voltage came back - presumably the glow plugs coming on and then going off.
Trying again with a newly charged battery, this time when I turned the ignition on, the big voltage drop happened immediately (without turning the key to START) and there were no lights on the dashboard, and no sound from the starter.
I've checked the wiring physically (in so far as I can get to or see the starter) and everything looks fine. It was starting and running with no problems before I changed the alternator. The moment I reconnected the battery and turned the key after putting in the new alternator, the problems started. It is a 65A alternator replacing a 45A, but otherwise the same.
I checked the big cable from the battery + terminal and it is almost a dead short to earth when the ignition is on. One explanation of that is that the solenoid contacts are stuck closed (possibly fused) and current is going through the starter motor. But if this is so, why don't I hear the starter turning and why doesn't the engine crank?
If the solenoid contacts are open, then there must be a short elsewhere in the ignition circuit. Let's say that some component was weakened as a result of the reverse voltage, and finally blown by the higher current coming from the new alternator. If that component was shorting the battery to earth, then it would explain the clicking starter (not enough juice to crank the engine), the progressively worsening current drain, and the fact that the starter is not turning.
What experiment could I do to test this? If the starter was easy to take off and test on the bench, I would do that, but it looks like a bit of a job. I want to be very sure that the starter is the problem before doing that.
My first thought is just to go through the wiring diagram checking everything with the meter to try and find the short. Am I on the right lines?
Here's the background (partly detailed in Starting problem after alternator swap, but I've now eliminated the alternator).
A couple of weeks ago I cross-connected the battery in a perfectly understandable accident which could happen to anyone. Only for a few seconds, mind, but that's all you need. Having reconnected it the right way round, surprisingly, I was able to start and run the car, and in fact drove it around for several days.
However, the stereo was blown, and the alternator light was on and the meter confirmed no charge was getting to the battery. So I got a new alternator and put it in. On trying to start the car, it turned over once but gave up, and there was just a fast clicking from the starter.
The battery was now completely flat, so I put a new one in, and tried again. All I could get was the clicking - but the battery drained quickly. With the meter I could see that when I turned the ignition to START, the battery voltage dropped to 5V. If I just turned the ignition on, without starting, I saw a slight voltage drop for a few seconds and then a click and the voltage came back - presumably the glow plugs coming on and then going off.
Trying again with a newly charged battery, this time when I turned the ignition on, the big voltage drop happened immediately (without turning the key to START) and there were no lights on the dashboard, and no sound from the starter.
I've checked the wiring physically (in so far as I can get to or see the starter) and everything looks fine. It was starting and running with no problems before I changed the alternator. The moment I reconnected the battery and turned the key after putting in the new alternator, the problems started. It is a 65A alternator replacing a 45A, but otherwise the same.
I checked the big cable from the battery + terminal and it is almost a dead short to earth when the ignition is on. One explanation of that is that the solenoid contacts are stuck closed (possibly fused) and current is going through the starter motor. But if this is so, why don't I hear the starter turning and why doesn't the engine crank?
If the solenoid contacts are open, then there must be a short elsewhere in the ignition circuit. Let's say that some component was weakened as a result of the reverse voltage, and finally blown by the higher current coming from the new alternator. If that component was shorting the battery to earth, then it would explain the clicking starter (not enough juice to crank the engine), the progressively worsening current drain, and the fact that the starter is not turning.
What experiment could I do to test this? If the starter was easy to take off and test on the bench, I would do that, but it looks like a bit of a job. I want to be very sure that the starter is the problem before doing that.
My first thought is just to go through the wiring diagram checking everything with the meter to try and find the short. Am I on the right lines?
