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MG MGB Technical - General Car Problem

Here's a new puzzle for the wizzards on this board. My girlfriend's '86 Toyota Celica bit the dust the other day. It wouldn't start, or even try to start. None of the dash lights came on when you turned the ignition on. Yet the headlights and horn worked perfectly. There is a clicking noise when you first turn the ignition on (first click of the key) that comes from the engine bay, but when you actually try and crank the car, their is no noise at all.
Tried jumping it, and nothing happened. But a meter to the starter and it is getting 12 volts constantly but nothing jumps or moves at all when key is turned on or off (I could have been measureing form the wrong points). Then we tried to bump start it and it fired right up. But when I turned accessories like the fan or radio on the dash lights would flicker off for a second. So I'm thinking right now its the starter relay, or one of the relays that operates the motor. I'm going to scrounge pick n pull right now for some relay's. But if it isn't, any guesses. I thought starter solenoid, but then why wouldn't the ignition lights come on when the ignition was turned on. I guess it could be the igniton switch.
Give me your thoughts and advice.
Cheers
Bill
Bill Mertz

Sounds like a ground strap to me, either on the battery or the engine. Do the headlights dim at any point, such as when trying to crank?

Good luck,
--
Olly
Oliver Stephenson

I had an old Civic that did something similar...turns out it was a corroded main fuse which occasionally made good enough contact to start the car. Just a thought...
Al
Al McMillan

I have the full workshop manuals for the 1985 Celica. In these the ignition switch sends 12v from the 40A fusible link AM1 (white) out on its ST2 contact to the starter on what I think is a blue/white, no starter relay unlike most MGBs. That same fusible link seems to supply just the alternator (one of its two whites) and the headlamp washer motor. If it bump-started then the supplies to the rest of the engine must be OK.
Paul Hunt

Any chance that the battery terminals are corroded? Even if there isn't great clumps of gunk on them, inside the contacts between the cable end and the battery post could be causing your problem.
1. Remove the cables.
2. Use warm water and a mixture of common baking soda.
3. Thoroughly brush the entire are, being careful not to let any get into the electrolyte. [this will ruin the battery]
4. Use a wire brush on the posts, and inside the clamp. [they make tools for this]
5. Clean and dry all parts, and reattach.
6. I use a felt washer treated with an oil over the posts, which further discourages corrosion.
You still need a good battery, but a battery that won't crank an engine, can't be recharged either if connections are corroded.
Safety Fast
Dwight
Dwight McCullough

Oliver, the lights don't seem to dim on when you try and crank it. I wire brushed all the battery cables, and ground leads today, but still nothing. Unless there is another ground lead I missed. I also went down to the autoparts store and had the starter tested. I worked fine on their test bench. I'm now getting suspicious of the Ignition switch. Paul is there anyway to test the 40A fuseable link? It appears to have 5 prongs sticking out of it, so I can't really figure out how to test with the Ohm meter.
Also is there a good way to test the ignition switch?
Thanks
Bill
Bill Mertz

Use a voltmeter to track 12v through the link to the switch and from the switch (turned to 'start') to the starter. Make sure you get your probe on the spades as well as the connectors if you can, the problem could be a bad connection between the two. You could use an ohmeter to test the fusible link but marginal conditions can give misleading results, which is why I prefer to do 'real world' tests. This will show less than 12v, or nothing, if there is a problem with any component back towards the battery. If you get 12v right onto the spade of the starter and it still doesn't crank, then the starter solenoid itself is faulty.
Paul Hunt

This thread was discussed between 22/05/2003 and 24/05/2003

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