MG Midget Forum

Hey Everyone,

I've been working on my electrical system for the last month trying to figure out why my car won't turn over. I have power to most of the car (Fans, Lights, Dash, Blinkers, Horns, etc). What I don't have is the ability to turn my car over. When I turn the ignition, I get nothing. I did purchase an electric ignition since my original was missing when I purchased the car and have it installed correctly (at least I think). I do have an amplifier-looking thing that was just sitting in the engine bay when I got the car (Pics if it helps).

I have power going to the ignition solenoid, and power at the ignition, just nothing happens at all when I turn the key. Could I be failing at the steering column?

Also, in the picture I attached, the second fuse from the firewall has no power going to it. Does that only get juice when the car is running?

I have gone through countless wiring diagrams to no avail. I'm hoping someone around here has some advice.

Jon

What car are you working on?

You have power to the ign sw, do you have power coming from it to the solenoid?

You need a hot ign feed to the solenoid when you turn key to start position in order to close the solenoid and have it provide power to the starter.

Have you jumped the solenoid to provide power across the main terminal?

Do you have a ground strap on the motor to the chassis?

Bottom fuse should always be hot
Second up is hot with ignition on.
Top two are for the lights and the fuses are bridged.

Sorry, just saw this is the midget forum, above is on the later B’s

---

1978 MGB
When diagnosing issues related to running and stalling, always check to see if you have gas in the tank first.



Edited 1 time(s). Last edit at 2022-08-14 08:18 PM by Bob Allen.

Its a 79 California 1500. I have not tried to jump the solenoid (just not really sure how to but I'm sure YouTube can help).

I'm assuming if I jump the solenoid I can isolate where the problem is?

No but it’s a start.

First, when you turn the key to start is there voltage on the ign wire to the solenoid?
That’s the small wire connected to the solenoid.

Should be, I'll have to double check.

JON , Here. Motor should turn over.

---

IN ALL SUBJECTS.: For those who believe, no proof is needed. For those who don’t believe, no proof is possible.

"Strive for perfection in everything. Take the best that exists and make it better. If it doesn't exist, create it. Accept nothing nearly right or good enough"
Sir Henry Royce
co-founder of Rolls-Royce .

"I take no credit for my own, of another man's fame".
Joe Baba 2021



Edited 2 time(s). Last edit at 2022-08-15 12:01 AM by oleanderjoe.

Thank you so much for this! I'm still trying to figure out the amp as it doesn't really show it in my manuals or anywhere else for that matter. I left it off, not knowing what the heck it was for.

Post a picture of the "amp".

Also, does the starter spin if you jump across the two largest electrical contacts bolts on your solenoid? (Watch out for the spark!)

Posted a picture of the "amp" as well as the solenoid and the electronic ignition. I'm not really 100% sure which bolts to arch. I'm assuming its the large bolt that goes to the starter and the one that feeds off to the ignition?

I really do appreciate the help.

One large lug on the solenoid should go to the battery. The other Large lug should go to the starter.
You jump across the two BIG terminals-in essence you are connecting the battery direct to the starter to see if the starter spins.
Use a large gauge insulated wire and make momentary contact.

As I said above in post #2 and #6, you also need to check and see if you have voltage at the small wire from the ignition when you turn the key to start, Not just the On position but to Start. It will ONLY have power when the key is turned as if you are starting the car.
That voltage closes the circuit on the solenoid as the diagram in #8 shows you and provides power from the battery to the starter.

I jumped the solenoid and got momentary sparks but the starter didn't do anything. I'm guessing the started might be bad?

OK, we have the answer to step one: connecting those two big terminals together at the solenoid bypassed the solenoid to confirm it was not the issue. If the starter did not spin then either the starter is jammed, or has no ground, or is bad internally.

Make sure it is not jammed: put the transmission in gear, parking brake off and try to move the car forward/backward and confirm the engine turns while doing this. If so, then the starter is probably not jammed.

Take a suitably sized wrench and turn the shaft that sticks out the forward end of the starter. If it turns freely then starter is not jammed.

Make sure to take the transmission back out of gear and reset the parking brake when done with this check.


Next:
Make sure the starter has a good ground: with a jumper cable, attach one end to the starter housing and the other end to the battery NEG terminal.
With the other jumper cable, connect one end to the battery + terminal and CAREFULLY touch the other end of it to the lug on the top of the starter where the big black wire from the starter solenoid is connected to the starter. If the starter still does not turn or make any noise, then it is bad internally.

So that you better understand what's going on here, the starter solenoid is actually comprised of 2 separate circuits (systems) internally. The first is the electromagnet inside the component. It draws a relatively small current when you turn the key to the start position. Electrical current flows through the key switch to this electromagnet only while the key is turned. When this happens, the electromagnet becomes energized and what was an innocuous coil of wire inside there turns into a very strong magnet, but only while the key is in the start position.

The magnetism created by this coil then pulls another, very LARGE electrical contact to connect with another. A noticeable "click" can be heard when this contact is pulled. It is through these two LARGE contacts that current for the starter flows from the battery.

By shorting across these large contacts, you are simulating the action that is supposed to be happening inside. In other words, you are providing a path for current to flow from the battery to the starter. You are proving an external bypass path around the 2 large contact that are supposed to be providing that path inside the solenoid.

The fact that you got a spark confirms that you do have current flow through the starter - that means your chassis ground is good. The fact that the starter didn't spin means that it is most likely jammed, a common occurrence if you've attempted to start it while the flywheel was still spinning. The Bendix gear that engages to turn the fly wheel gets jammed rather than sliding into place. Kerr details how to free the jam in post #14. Essential, with the break off, just put the car in a high gear (easier to push the car), and rock the car back a bit. If the starter is jammed, this ought to free it up so the Bendix gear can retract back into place.

If this doesn't do the trick, then your starter probably has an internal problem that's jamming it.

BTW, when turning the key to the start position, if you don't hear a click from the solenoid (refer to paragraph #2), you may also need a starter solenoid too.