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jumping relay ?

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jumping relay ?
#1
  This topic is about my 1974 MG MGB GT
tommylg Avatar
tommylg tom greene
murfreesboro, TN, USA   USA
I was getting an intermittent start with the key - nowI have a no start from the key.
I can jumper brown/white (#87) to either bottom fuse and it starts.
All four wires on the ignition switch light.
All wires at the starter are secure.

Question: when i jumper brown to yellow/brown the relay clicks - what does that mean?
Thank you, Tommy

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dickmoritz Avatar
dickmoritz Platinum Member Dick Moritz
Philly 'burbs, PA, USA   USA
Check at the starter relay for the white/red wire to see if it receives power when the key is in the Crank position. If so, and if the engine cranks when powering the white/brown wire, then the starter relay is bad. If no power to the white/red wire when the key is in the crank position, then you'll need to trace the wiring between the ignition switch and the relay,..,.

Dick



Errabundi Saepe, Semper Certi
(Often wrong, but always certain)

jjonns74 Avatar
jjonns74 Gold Member John Dailey
Indianapolis, IN, USA   USA
1974 MG MGB "Athena"
1974 MG MGB "Apollo"
In reply to # 3737301 by tommylg I was getting an intermittent start with the key - nowI have a no start from the key.
I can jumper brown/white (#87) to either bottom fuse and it starts.
All four wires on the ignition switch light.
All wires at the starter are secure.

Question: when i jumper brown to yellow/brown the relay clicks - what does that mean?
Thank you, Tommy

Tommy

Sounds like you still have the Seat Belt Module in the Start circuit.

The White/Red wire from Ignition Switch (Start position) goes to the Module.
Module output is the Yellow/Pink (may look Brown to you) wire, that goes to terminal W1 of the Starter Relay (to "trigger" same).

When you jump Brown to terminal W1, you are bypassing the Module - and directly energizing the Starter Relay (hence, the Click).

When it Clicks, it should be allowing the 12vdc (Brown feed) at terminal C1 to contact to C2 (White/Brown) that powers the Starter Motor (providing all wires are connected to the Starter Relay).


Many remove the two wires from the Seat Belt Module & jumper them at that point (bypassing the Module).


Of Course ---- Your Battery Must Be Fully Charged. All connections at the Starter Solenoid must be Clean & Tight.

Edit: Bottom Line:
What does it mean??
Jumpering White/Brown to 12vdc (Brown fuse, etc) > Starter spins = Solenoid & Starter are OK
Jumpering Brown to Relay terminal W1 (Yellow/ Pink) > Relay Clicks = Relay OK

Conclusion: 12vdc from Ignition Switch is not getting to the Starter Relay -- most likely the Module.


John



Edited 1 time(s). Last edit at 2018-05-16 11:48 AM by jjonns74.

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tommylg Avatar
tommylg tom greene
murfreesboro, TN, USA   USA
Got it!
My seatbelt module has been disconnect since day 1.
However, I have been behind the console and the yellow/pink wire was bare and grounding against the body. Taped it up and we have start!
Thanks much, Tommy

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