• Hi Guest!
    You can help ensure that British Car Forum (BCF) continues to provide a great place to engage in the British car hobby! If you find BCF a beneficial community, please consider supporting our efforts with a subscription.
    There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Subscribers don't see this gawd-aweful banner
Tips
Tips

Starter rely problem?

Share this page

Guinn

Guinn

Jedi Warrior
Offline
I appear to have a starter relay problem. When I attempted to start this PM, starter engaged then disengaged before engine start. A second turn of the key gave me nothing. No click, no hum, no change in the voltmeter which read 12V on the nose.

I know it could be the solenoid but suspect the relay. Any other ideas?

Can someone tell me the location of the relay on a 78B? Better yet post a picture that shows the location?

Thanks, guys,

Guinn
 
The ignition and starter relays are located on the passenger side fender wall near the fuse box. The starter relay has a white/red wire going to it. Use a test light or meter to verify voltage to and from the relay.
 
Thanks, Kimberly. Even though I am colorblind, I should be able to spot a white-red wire! Will let you know results.

Guinn
 
Guinn said:
Thanks, Kimberly. Even though I am colorblind, I should be able to spot a white-red wire! Will let you know results.

Guinn
Click to expand...

The white/red wire is connected to pin 86 or W1 depending how the terminals are marked on the relay. If possible have someone label them for you. With age and oxidation it maybe easy to mix the white/red wire with the white/brown wire.
If you look at the wiring diagram in the link I provided above, there is a typo. It should be a white/brown (WN) wire connecting to pin C2, not brown/white (NW).
 
Thanks again, Kimberly. I made a jumper and shunted the white-red to the brown and the starter worked OK. Now that I had proved the relay was the problem, I did order one from Brit-Vic, then autopsied the old one by cutting around the base, like taking a lid off the old 35mm containers. I found that the major wire from pin 86 had come loose. Soldered it and hot-glued the case back on, reattached the wires and it works like a charm! Will keep it for a spare.

These things are fun if you have a few tools, aren't they?

Guinn
 
Fun, that is the name of the game, that and satisfaction.
 
Guinn said:
Thanks again, Kimberly. I made a jumper and shunted the white-red to the brown and the starter worked OK. Now that I had proved the relay was the problem, I did order one from Brit-Vic, then autopsied the old one by cutting around the base, like taking a lid off the old 35mm containers. I found that the major wire from pin 86 had come loose. Soldered it and hot-glued the case back on, reattached the wires and it works like a charm! Will keep it for a spare.

These things are fun if you have a few tools, aren't they?

Guinn
Click to expand...

Why pay shipping for a relay? Replacement relays are available at local chain auto parts stores for less than $5-
Just ask for a generic Bosch style relay.
Here's a listing for one available at Schuck's.
https://www.partsamerica.com/ProductDetail.aspx?MfrCode=OPR&MfrPartNumber=A715&CategoryCode=3443
 
Guinn said:
....then autopsied the old one by cutting around the base, like taking a lid off the old 35mm containers. I found that the major wire from pin 86 had come loose. Soldered it and hot-glued the case back on, reattached the wires and it works like a charm! Guinn
Click to expand...

The mark of a true scientist. Don't just dump the bad part, learn from it!
 
That MacGyver will outlast the "new" white-box unit by years, too.
 
I do enjoy these little challenges - except when it stops me from driving!

Thanks, Kimberly, for the info about Bosch relays but have already ordered one from BV. I guess I could return it as not needed and just pay the shipping, couldn't I?

Guinn
 
Back
Top