SOLVED - Calling all electrical experts... I broke something, starter won't engage

[milwaukeesk]

Thanks everyone! Problem has been solved. Starter is good, ignition switch good. Issue lied with one of the relays which was sorted with a simple jumper. I'm back up and running.... and have a better understanding for the wiring on a '74 e9 that I ever thought i'd get.

 

[bavbob]

I have a learning curve thanks to Don...I wondered if the car was originally an automatic as well. There is an additional relay for automatics that should receive 12 V at all times to function. Anything less and the starter is dead in the water.

 

[HB Chris]

So which relay needed a jumper? It would be good if you posted pics of the 74 relays like I did so we know the locations as well.

 

[milwaukeesk]

So which relay needed a jumper? It would be good if you posted pics of the 74 relays like I did so we know the locations as well.

In the 74 under the dash, left of the fuse box along the side where the hood release hangs their are 6 relays. [from front to back (firewall) are 3 identical relays, 1 wiper/washer relay, 2 identical relays]. The relay that I jumped was the relay closest to the firewall, all the way back.

Apologizes for the poor pictures. Relay in question is the one closest to the fuse box.

 

[tmason]

I'm having a little issue with mine not turning over with turning the key to start. It seems when it gets hot it takes 2 or 3 times to start. I did a auto to manual conversion. Thanks Tim

 

[milwaukeesk]

I'm having a little issue with mine not turning over with turning the key to start. It seems when it gets hot it takes 2 or 3 times to start. I did a auto to manual conversion. Thanks Tim

Sounds like a different issue than mine. Without knowing more i’d start with your ignition switch. Without knowing more, if the starter is engaging just not starting, it could be host of issues such as distributor/plug wires.

 

[sfdon]

I have a learning curve thanks to Don...I wondered if the car was originally an automatic as well. There is an additional relay for automatics that should receive 12 V at all times to function. Anything less and the starter is dead in the water.

Not correct.....
It’s a funny setup. That relay gets ZERO voltage unless the key is turned to crank.

12v from switch at pin 30 when key turned to crank.
Pin 30 is jumpered to pin 86
Pin 85 is ground to relay from auto tranny
Pin 87 is output to starter.

Voltage only when turning key.


‘73 is different-
red from fuse 5 to 30
Black from switch to 86
Black to starter from 87
Brown/black from tranny pin 85

 

[Drew20]

Think that's the starter relay? Which ensures you can only start when in "park" or "neutral". Not needed in a manual car, think the manuals don't have it, not sure

A switch on the auto gear selector sends an earth signal to the relay which allows the relay to pass current from ignition switch to starter solenoid

 

[sfdon]

Chris was kind enough to share the extra big ‘74 schematic- makes it lots easier to identify and troubleshoot.

 

[Teej]

Must be something in the air.

My e9 conked out the same way today. Sounded like a relay POPPED when I went to start the car while parked at an errand run.

Now I get the dials and gauges turning on and a click at back, sometimes a single click at the starter if I let the ignition stay on for a bit. It’s still hot now so I’ll see when cold, meanwhile read threads...

 

[stphers]

12v from switch at pin 30 when key turned to crank.
Pin 30 is jumpered to pin 86
Pin 85 is ground to relay from auto tranny
Pin 87 is output to starter.

Voltage only when turning key.


‘73 is different-
red from fuse 5 to 30
Black from switch to 86
Black to starter from 87
Brown/black from tranny pin


And the funny bone is connected to the elbow bone, the elbow bone is connected to the arm bone and the arm bone is connected to well, you know
Sorry couldn't resist

Rick