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MG Midget and Sprite Technical - Need Help With Last Piece of Ignition Puzzle

Thanks to those who replied to an earlier post that lacked the detail I now have. I fried my starter solenoid some time ago by cranking the starter too long with the positive electronic ignition wire off the coil (unbeknownst to me). I have replaced the starter solenoid and have wired it as shown in the pictures and as the old solenoid was wired. These are the tests I have performed so far:
1. Jumper between positive battery terminal to power terminal on starter motor turns starter motor/engine.
2. Jumper from positive battery terminal to power cable/terminal on starter solenoid turns engine.
3. Screw driver across starter solenoid power in/power out terminals turns starter motor/engine.
4. Grounded multimeter on white/red wire when detached from starter solenoid reads .01 volts when ignition is off.
5. Grounded multimeter on white/red wire when detached from starter solenoid reads 12.30 volts when ignition key is fully on.
6. Jumper between positive battery terminal and ignition terminal on starter solenoid (where white/red wire attaches) produces no "click".
This feels like a grounding issue, and I'm going to remove the solenoid scrape more paint and reattach while waiting for a better advice from smarter guys. Thanks in advance for the help.
Steve





S. G. Mauer

I can now add that the starter solenoid is well grounded to the body with no change.
S. G. Mauer

Obviously, the most important part of my story is the part I left out. When I fully engage the ignition (key) with everything connected nothing happens. The red ignition warning light comes on but then nothing.
S. G. Mauer

Have you checked your ignition switch itself and also its connections?
Nigel Atkins

ETA: I'm guessing it's a USA car but the year could help with wiring and colours.

Putting up a Vehicle profile for others to view might say you repeating this info, (with those that look at the profile).
Nigel Atkins

Nigel, sorry to jump in on your question but Steve does say he gets 12.3v at the white/red wire at the solenoid when the ignition switch is fully on. Fully presumably means when turned to the operate starter position, not just ignition.

If the solenoid body is now earthed properly to the car through its fixings, and the white/red is attached to the correct terminal of the solenoid, then it just sounds to me it must be a faulty solenoid.
GuyW

Steve

When you say that the solenoid is now well grounded with no change, is that just trying the ignition switch, or have you repeated step 6 with the jumper?

Although you are getting 12v on the white red with a multimeter, that is without a load applied. Check the voltage on the white/red when it is connected to the solenoid. If you still get 12v, it does sound like a faulty solenoid.
Dave O'Neill 2

Tending to Guy's view because of No.6 on Steve's original post.
Greybeard

I can't get my brain to interpret the photos as a version of the starter solenoid that I am familiar with. It may just be the angle of the shots, or perhaps its a different sort than I am used to. But is the white/red wire connected to the correct terminal?
GuyW

Check resistance from red/white terminal to metal body - should be only a few ohms. If not the solenoid coil or an internal connection is faulty.
Bill Bretherton

I must admit I was rushing but I don't trust meter readings completely, 0.1v when off, and only 12.3v on.





Nigel Atkins

Just to check if it might be a weak supply from the ignition switch in the start position

Try poking a screwdriver in connecting the power in terminal with the large red wire to the blade terminal with the white/red wire----if the solenoid is ok it should click in and wind over
If that works the switch or connections are playing up
If it doesn't work either the solenoid is faulty or not earthed

willy
William Revit

Why are there no rubber boots on these terminals and why is the heavy duty braided wire to the starter motor completely un-insulated?
Also, some starter solenoids (1500) have an extra connection to short out the in loom dropper resistor and yet others (not Spridget) have connections to disconnect power to lights etc. when starting. These types of solenoid will not work properly if the Red/White wire is on the wrong terminal.
Rob
MG Moneypit

Rob I think the braided cable is an earth strap in the background,nothing to do with the starter motor cable which has a black covering.

But I agree about the white/red wire possibly being wrongly connected.
Should the white/red and white/green wire connections be swapped over. Its hard to tell from the photos.
GuyW

Sorry about the missing vehicle information... 1976 1500... LHD
S. G. Mauer

No problem with vehicle info but a phone photo is wrong orientation is a sin! 😁

I think the White/red is ok as it's opposite the White/light green but there does seem a lot of thick cables.

I think the double brown with the elbow connector would sit better facing up rather than down.

Big blobs of solder don't inspire perhaps the joints are dry or otherwise poorer connections, apparently some of(?) the more recent (last 10, 20 years?) starter solenoids can get cruddy inside themselves causing bad connections, if you could get a know good one to compare against you might find an answer, or take it to bits, or replace it with new.

If Willy's thinking the same as me I know I'm not having one of my many brain-farts, next I'll be showing him how to set the carbs without the pins (not). 😁


Nigel Atkins

>>S G Mauer wrote>>
6. Jumper between positive battery terminal and ignition terminal on starter solenoid (where white/red wire attaches) produces no "click".

Assuming (a) the solenoid's body is properly grounded; and (b) the jumper lead is sound; and (c) the jumper is touching the 'starter solenoid winding terminal' (and not the solenoid's ballast terminal) . . .
then unequivocally the solenoid is faulty if its doesn't click (its internal coil winding is most likely faulty 'open circuit').

The solenoid's internal coil winding can be tested by first disconnecting the low current leads from the solenoid, then putting the DVM (test meter) onto low ohms setting, one test lead on the 'starter solenoid winding terminal', the other lead on the solenoid's metal body. A working solenoid will show 2 or 3 ohms. A faulty solenoid will show a much higher reading (including infinity, aka 'open circuit).
J Thomson

Had one of these solenoids once that had been riveted to the plate 180deg about face. took ages to work out what was going on--
To check, remove both the Wr and Wg wires and with the battery disconnected, with your multi meter measure each of both these spade terminals to ground one at a time
The W/g terminal should be open circuit
The W/r terminal should have a resistance because you're measuring the coil inside the solenoid to earth through this terminal

AND--
Looking at Nigel's pic of your solenoid, that double brown wire (red/yellow arrowed) that's onto the power end of the solenoid looks to have missed the spade terminal with the spade poked up inside the insulated cover and maybe no, or little contact there----easy mistake to make but 'could' be the cause of your issues

willy
William Revit

Success!!! Thanks to all who offered assistance with this frustrating issue. It turns out that I received two non-functioning starter solenoids from the same supplier. The third from a different manufacturer worked perfectly and the car started instantly. I almost had a stroke it surprised me so much! If nothing else I learned a little about chasing electrical problems and a lot about being patient. Thanks again.
Steve Mauer

This thread was discussed between 15/10/2021 and 25/10/2021

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