Engine wont turn off... switch or backfeed? - Defender Source
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Old September 14th, 2016, 07:26 AM
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Ed Mistler
88 D-110 station wagon 2.5TD
Join Date: Aug 2015
Location: Pittsburgh, PA
Posts: 32
Engine wont turn off... switch or backfeed?

I have a puzzling electrical issue that I hope someone has seen and fixed before :-)

'88 110 with 19J:

Starts and runs fine, but when I turn the key off, and remove the key, the battery indicator light comes on and the engine still runs...
if I remove the wire to the solenoid (or just loosen the nut) the engine turns off.

This is intermittent. Sometimes, the engine shuts off while I'm getting ready to stall it, sometimes if I wiggle the key back and forth in the ignition, the engine shuts off. A few times, I could push the rear washer button and the engine would shut off (all of these could be coincidence, since nothing is consistent). Sometimes the engine shuts off normally.

Does this sound like the ignition and if so, can I just replace the switch in the back of the ignition? Or is this the problem that I've read about where there is backfeed from the alternator to the cutoff solenoid, in which case I need a diode? Does the lit battery indicator give me a clue? (I'm not very good at electrical issues... but I find myself staring at the wiring diagram late into the night ) Would checking the voltage at the solenoid help deciding between ignition/backfeed? (ie. 2volts is backfeed, 12 volts is ignition?)
Or is this a ground issue (seems to be a common culprit in most electrical issues), in which case I have to find out where the grounds are:-))

Also, am I doing any damage by stalling every time I stop?

Any help would be appreciated!

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Old September 14th, 2016, 07:36 AM
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Robert Davis
Join Date: Oct 2004
Location: USA
Posts: 5,020
Your ignition switch is flaky.
You can replace it or install a "one way" diode on your charge indicator light from the alternator which may compensate for the faulty switch position.
The best solution is to replace the IG SW because if it still supplies juice to the solenoid with the key switched off, then it will also run your battery flat.
Off is off and on is on, but in your case, when off is still on, then off is not off, it's on when it should be off.


Uncle "Richard" Douglas has a Land Rover with big wheels that never gets stuck... until he breaks something so it won't go. Uncle Douglas always breaks something. - Anna Crowther at the Conclave 2012 (AKA Carburetor Neck)
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Old September 14th, 2016, 07:41 AM
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1994 NAS D90 #1919
Join Date: Mar 2015
Location: Pittsburgh, PA, USA
Posts: 91
Hey Ed - It would seem to me that since the ignition barrel is a switch that opens and closes, if it was functioning correctly it would cut the power when you turn it off and remove the key. I would replace it since they are relatively inexpensive. I'd also test for the ground and back feed issues while you're at it.

Let me know if you would like another set of eyes (and tools) to help sort it out. I'm in Wexford.
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Old September 14th, 2016, 08:02 AM
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John B.
1991 Defender 90, 200TDI
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Location: Calgary
Posts: 7,910
Probably the switch but you should test it first with a meter. The start relay could be sticking (if your truck has one).
Pissing people off on the "net" since 1983.

Land Rover. Turning owners into mechanics since 1948.
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Old September 14th, 2016, 08:09 AM
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Join Date: May 2010
Location: Arlington, VA
Posts: 4,577
er...wait...is your alternator output connected directly to your fuel stop solenoid?
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Old September 14th, 2016, 08:15 AM
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Uncle Douglas
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Doug Crowther
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Old September 21st, 2016, 06:37 PM
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Ed Mistler
88 D-110 station wagon 2.5TD
Join Date: Aug 2015
Location: Pittsburgh, PA
Posts: 32
Thanks for the help!

While I'm tracking down a new switch, I decided to poke around with a volt-meter.

Would this change anyone's mind, or is it still the switch?

Volts measured at the cut off solenoid.
1. key in off position (truck not running): 0 volts
2. key in on position (truck not running): 12 volts
3. key in on position (truck running): 14 volts
4. key in off position (truck running): 1 volt

and interestingly, if I put a pair of pliers on the solenoid nut, the truck shuts off.

Can the switch be supplying 1 volt when the truck is running, but not when not running?

Thank you!
(electricity is not my friend)

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Old September 22nd, 2016, 12:15 AM
Greg S
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Greg Sutfin
1986 90
Join Date: Oct 2011
Location: Duncan, British Columbia, Canada
Posts: 82
Sorry! I have to say it.
Check your ground connections. You NEED a ground from battery to motor heavy enough to start the engine. You ALSO need a ground connection from the battery to the chassis.

I once tore a ground wire off and when I stopped and turned off ignition the diesel engine kept running until I shut off the headlights. Stop solenoid was acting as a earthing route for the headlights, in other words, the headlights were powering the solenoid.

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