Electrical problem: car wont start

[jjbunn]

I'm still trying to diagnose what is preventing my TR6 from starting. A week ago, the engine turned over a couple of times on the starter motor, didn't fire, and then everything went dead: fuel pump stopped pumping, large current draw on battery. I charged the battery, and turned the engine a little by hand. With the charged battery installed, the fuel pump pumps, hazards work, headlights work. But the starter motor wont energise: it's as if it's shorted or something.

I'd welcome some advice on how to debug this problem. How can I check the starter motor is OK, for example?

 

[Guest]

Run a wire from 12v to the starter direct.

If it's dead, but works when you run a live wire to it, assuming your grounds are all attached, it's probably the key. Mine went out at just the wrong moment a while back...

If it 'clicks' when you turn the key, it is likely the solenoid.

 

[tomshobby]

Try cleaning the battery connections. You are describing what happens if they are corroded.

 

[Brosky]

1. Follow Tom's advice first

2. If #1 didn't work, follow Alan's advice.

 

[Andrew Mace]

Yep. Check the battery connections...on BOTH ends of the battery cables, as well as major grounds and all starter and solenoid connections. Oh, and check the battery cable terminals themselves, most especially if by chance one of the battery cables has one of those clamp-on "universal" replacement ends on it. PLEASE don't make me repeat how I know about these things. /bcforum/images/%%GRAEMLIN_URL%%/blush.gif

 

[TexasKnucklehead]

Julian,
My brother once changed a starter 3 times in the same day. Each time, taking the old one back to the parts house and getting a new one, because that one didn't work either. Finally the guy behing the counter showed him the new starter worked. He took a pair of jumper cables, attached to a battery on one set of ends, and the other attached to the starter to see the starter spin. (It will spark a little, but it won't hurt you if you're careful and stay insulated and have the starter secured.)

After that starter still didn't work on his car, he replaced the ground cable to the battery and the starter worked fine. The grounds have a tendency to corrode internally and will not provide a good electrical path. A little resistance at a high current will be a large voltage drop and the starter will not turn.

I don't think Triumphs employ a fuseable link, but my Dodge had a small crimped link inside the cable housing that corroded, causing much consternation.

Does your lights dim when you try to start it?

 

[jjbunn]

Thanks for all the suggestions. As soon as the weather clears up I will follow up with what I find.

 

[jjbunn]

I'm still having problems with this.

I've replaced the battery, and the +ve battery lead to the starter motor.

With the battery lead disconnected from the starter, if I connect the IGN terminal to battery + then the starter solenoid operates. However, with the battery lead reconnected, nothing happens.

The resistance of the solenoid (IGN terminal to ground) is about 0.7 Ohms: seems OK, and I don't think the solenoid is the problem.

The resistance from the starter motor's battery terminal to ground is infinite, which seems OK: the solenoid is disengaged.

I've checked all the earths from battery -ve and remade them.

I have a horrible feeling that the starter motor is buggered, that it presents a dead short when the solenoid switches power to it.

BUT I have recently reconnected everything under the dash, and I wonder if I have got something wrong under there. What might that be, that explains these symptoms?!

Thanks!

 

[DougF]

Try tapping the side of the starter with a hammer while someone turns the key. Could be something hanging up or a dead spot.
The madder you are, the bigger the hammer.
If that works, it could mean a rebuild.

 

[AltaKnight]

Do your lights dim when you try to start it?

So do they????

You can always try using jumper cables to apply the juice right to the starter terminal (make sure it's out of gear first)

If you buggered something up under the dash then it would have to be the connections to the ignition switch; test whether you're getting voltage to the solenoid when you're turning the key

 

[DrEntropy]

Pull the starter motor, check the brushes and take a red ScotchBrite pad to the commutator to clean it.

 

[jjbunn]

Do your lights dim when you try to start it?

So do they????

You can always try using jumper cables to apply the juice right to the starter terminal (make sure it's out of gear first)

If you buggered something up under the dash then it would have to be the connections to the ignition switch; test whether you're getting voltage to the solenoid when you're turning the key

OK so I went to check the lights to see, and now I have no lights! The situation seems to be getting worse, and I am thoroughly confused /bcforum/images/%%GRAEMLIN_URL%%/confused.gif

I am going through Dan Masters' wiring diagram and measuring voltages, in an effort to understand what's going on.

I get voltage on the IGN wire of the starter when I turn the key. On the other hand I have no voltage at the headlight switch. Tomorrow I will re-check the ignition switch, but I can't see how that can be the problem since it is able to switch power to the starter solenoid.

 

[DrEntropy]

And the "obvious" has been checked: the battery terminals and connections to them, yes?

 

[poolboy]

I'm beginning to suspect the starter relay.

 

[jjbunn]

And the "obvious" has been checked: the battery terminals and connections to them, yes?

Yes ... I'm very confident of the connections.

 

[jjbunn]

I'm beginning to suspect the starter relay.

I will add it to my list of things to check out tomorrow! Thanks.

 

[TR3driver]

Still sounds like a bad connection to me, possibly inside the battery case. What does the voltage at the battery do when you try to start it ? How about the voltage right at the solenoid (to the starter housing) ?

 

[DrEntropy]

Ummm... nobody has mentioned engine grounding strap/wire... THAT can get ugly. "Other" things then try to carry the draw: Choke cable, fuel lines, throttle linkage...

 

[toysrrus]

Hi There,

I agree with Doc. The engine grounding wire could be the culprit?

If all else fails; Get that really "BIG HAMMER" and try to knock out the dead spot. My guru Brit Mech. taught me that a long time ago.

Good Luck,

Russ

 

[Brosky]

<div class="ubbcode-block"><div class="ubbcode-header">Quote:] Get that really "BIG HAMMER"[/QUOTE]

Ah, just a tip. Try a heavy plastic covered lead hammer if possible. I've seen hammers bounce off into starter wiring, etc. and you don't need any of that.