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MG TD TF 1500 - Starter Switch?

After a good 1 hour drive at speed yesterday I turned off the TD. When I went to restart it 20 minutes later the engine turned over as normal but didn't start (happens once in a while, so I wasn't surprised). Pulled the starter again and absolutely nothing happened. This morning I put a volt meter on the battery - it shows 12.64 V (car not running). It also shows an identical reading at the switch so I assume that the switch is getting enough power. I turned the starter with a wrench and it turns freely. I now assume that the problem is with either the switch (my guess) or the motor. Reading the archives it appears that I can test the switch by using a set of jumper cables. If the motor turns then the problem will be with the switch (correct?). Now the dumb question - before I start a fire, where exactly do I connect the cables? The switch has an incoming terminal from the battery and an outgoing terminal to the motor. Is that where I connect? The car is positive ground. Thanks all in advance .... Chris
P.S. the funny part of the story is that when it wouldn't start I just asked a couple of young lads to give me a push - they seem to get quite a thrill out of it and to be honest it's much easier than trying out the crank for the first time!!
Chris Malcolm (TD 29228)

....yes, your just jumping the two terminals....bypassing the pull switch...
gblawson(gordon- TD27667)

So Gordon, just to be sure - I only use ONE cable and connect the ends to the two terminals of the switch? ... Chris
Chris Malcolm (TD 29228)

Chris, to test the switch and the starter motor just leave the ignition switch OFF when you do the jumpers. The starter should crank but the engine won't run. Connect one cable to side of switch closest to battery. Then just "touch" the other end of the same cable to other end of switch for an instant - don't clip it on! If the starter turns it sounds like the switch is bad. (If you have a cuttoff device on the battery a safer way is to cut the battery off there FIRST, connect both ends of the cable with clips to either end of switch, then turn the cuttoff know on/off quickly to send the juice.) This will give you a "safer" feeling, trust me! (I know your fears having just melted a few new wires myself.) I'm sure Gordon and the others will tell you what to do next.

Ed
efh Haskell

To add one more thought - after checking that I had 12v to the switch - I put my volt meter on the outgoing post (towards the motor), set the other lead to ground; pulled the starter and nothing happened - no current at all. Can someone confirm that this has to indicate a burned out switch? and yes, Ed, I'm trying to avoid the jumper cables!!... Chris
Chris Malcolm (TD 29228)

hello chris, if you were pulling on the starter handle/knob enough for the contacts in the switch to "make", sounds like a bad switch. regards, tom
tom peterson

Okay, here goes. If your voltmeter has a "continuity test" feature simply FIRST disconnect the battery for safety then test continuity between the 2 terminals on the switch in it's open and closed positions. You should have continuity when you pull the cable only, meaning the switch is working. Also, you probably know this, but if working alone you can just push the metal bar protruding from the front of the switch yourself. Same thing as pulling the cable.

My switch was sending juice up the cable & causing a massive short during reintstall a few weeks ago. Cable actually got very HOT! I couldn't duplicate it so I just bought a new switch. So I guess they do go bad. There is a picture in the archives somewhere of one that caused an engine fire! Scary device. Listen to these other guys though, I'm just a novice.

Hope this helps,
Ed
efh Haskell

Chris,

You can try to push hard on the test button on the switch to see if it closes, this button is the small rod which you see in between the two terminals. if that doesn,t work, short out the two terminals with a fat screwdriver.
Make sure the the car is out of gear beforehand.


John

J Scragg

Thank you again everybody. So far I have determined that my problem is not the switch. I have continuity through the switch (using a multimeter) plus shorting across the terminals does absolutely nothing at all. I used a combination of Ed's advice and turned off the battery cutoff switch, then wired the lead from the battery directly to the second terminal (the reason being that I had no jumper cables, and John, I couldn't get a screwdriver across the terminals - this was just quicker and easier), then turned on the battery cutoff switch and nothing happened. I then measured the voltage at the second terminal and it had dropped off to almost nothing. I then disconnected the lead from the second terminal that goes to the starter motor. When I did that the volts jumped up to over 12 again (on the second terminal). I guess that my next test will be to borrow a fresh battery just in case that is my problem - if not then I'll tackle the starter motor. ... Chris
Chris Malcolm (TD 29228)

Chris, The very first simple test you should always do with a problem like this is to just turn your headlights on and then try to start your car. If the lights go dim, but the starter does not turn, then you know that the starter is drawing current but has a malfunction. If there is no change in the head light intensity, then it is most likely an open in the starting circuit (bad switch, open connections etc.) Cheers Phil
Phil Atrill

Phil,
Thanks for that. The lights go almost out when I try to start. So tomorrow I'll see if I can get the starter motor out. . ... Chris
Chris Malcolm (TD 29228)

Chris,
If your starter motor is in fact bad,,, You can get a much less expensive starter from an MG midget,, It fits and looks very much like an origonal,, I have been using them for years,,, The only mod that it needs is to file down the head of one of the screws that might interfer with the backing plate on the engine,,,
STEVE WINCZE

Chris, The headlight test I recommended assumes that your Battery is OK. But since the lights went almost out and not just dim, I would substitute another battery known to be good before monkeying with the starter. Cheers Phil
Phil Atrill

The fact that you are reading 12+ volts from your battery, leads me to believe that you need a new one...
12V batteries, with no load , should read over 13volts. That doesn't mean that it is THE problem, but it would contribute to poor starting.
Edward
E.B. Wesson

A final summation and again thank you to everyone for their advice. The winner of "guess the problem" goes to Edward and Phil. The battery is shot. This morning I had a friend stop by and we tried a jump start which worked like a charm. ... Chris
Chris Malcolm (TD 29228)

This thread was discussed between 29/05/2011 and 31/05/2011

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