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Yesterday - introduction, today - question re: ignition wiring

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rustbelt Silver Member Len Norris
Flushing, Michigan, USA   USA
1977 MG MGB "Speckled Hen"
Have a few questions regarding the rewire advice found in the search section that cures the 'car keeps running after key is off and removed' issue. My 77B has the ignition switch relay, which I understand was a new feature in late 1977, but unfortunately, created the issue I am having. The cure appears to be a 5 minute job, requiring the moving the small white w/ brown stripe wire from the fuse box to the ignition switch relay next to it. The instructions are called: MGB Ignition System Feedback, found in a 5/17/11 post titled 'Car won't shut off'.

I am replacing my fuse box (did some research - going with Moss) along with the ignition switch relay (also Moss). Fuse box terminals are somewhat loose and the relay switch is corroded at the terminals. Also looking to clean up the appearance.

The wires going into my current fuse box do not sound like they match those in the instructions. If someone could take a look at the picture I've drawn and tell me if anything looks incorrect, I'd appreciate it. Also included is a drawing of the ignition switch relay. I'm prepared for the comments about my drawings, so let them fly......lol
thanks, Len

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Ex-Calif Avatar
Ex-Calif Gold Member Dan D
Cincinnati, Ohio, USA   USA
1968 MG MGB GT "Bart - Yellow And Naughty"
1977 MG MGB "Red Betty"
2012 Jeep Liberty "Tank"
2014 Hyundai Accent "Skate"
Hey Len,

You will hear about a "diode" fix that does work but it is time consuming and takes more effort.

I used the procedure linked below. It was quick and easy. The article is 3 pages long but the bottom line answer is in the last paragraph.

http://www.mgexp.com/phorum/file.php?1,file=140904,filename=Ignition_Feedback.pdf

I did this on my 77B shortly after I got it. No issues since.



The goal - Reliable summer driver interspersed with mechanical tinkering...
Motto - "Driving fifty in the twisties..."
On Mods - It's your damn car - Do what you want. Haters gonna hate...
On SUVs - Drive your B like a soccer mom is texting her friends about how she wants to kill you...
Red Betty - http://www.mgexp.com/registry/GHN5UH418165
Bart - http://www.mgexp.com/registry/GHD4U146898G

rustbelt Silver Member Len Norris
Flushing, Michigan, USA   USA
1977 MG MGB "Speckled Hen"
Thanks Dan for the response, I appreciate it. The instructions you attached is what I am working off of.
The instructions say that there are 3 white/brown wires going to the left side, second from bottom circuit of the fuse box.
My car has 2 white/brown wires going to that circuit and 1 white/brown wire going to the bottom circuit on the same side.
I'm hoping someone might notice that is wrong and advise me on what to do. Wish I had the fuse box picture turned so it could be read better.....

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Ex-Calif Avatar
Ex-Calif Gold Member Dan D
Cincinnati, Ohio, USA   USA
1968 MG MGB GT "Bart - Yellow And Naughty"
1977 MG MGB "Red Betty"
2012 Jeep Liberty "Tank"
2014 Hyundai Accent "Skate"
Ah - OK - got it.

The brown whites on the fuse box do 3 circuits - one is from the ignition relay and with the ignition switch on this supplies power to all the green circuits - I am presuming that all the green circuits work with the key.

The second circuit supplies the ignition - the one we are trying to fix.

The third is the circuit for the fans.

It looks like the OP has moved the fan circuit from the second from the bottom (ignition switched) to the bottom (brown circuit) - this means the fans will work with the key off.

Some guys prefer this such that the fans will continue to run after shutting the car off and continue to cool the engine. I don't subscribe to that theory and would recommend putting the brown white on the bottom circuit back where it belongs.

The other circuit that needs to be investigated is the solid red circuit on the second from the bottom (switched) - This is probably something added by the OP and instead of picking an appropriate color he just went with solid red wire. Reds on the MG usually relate to dash lighting.

I try to pick an appropriate wire color - i.e, switched would be white. If he connected that on the green side (switched and fused) I would use green wire.

Anyway to fix the ignition issue is still the same - one of the brown/whites at the fuse box will be a double. You cut the thinner gauge one and double it to the white on the igntiion relay.



The goal - Reliable summer driver interspersed with mechanical tinkering...
Motto - "Driving fifty in the twisties..."
On Mods - It's your damn car - Do what you want. Haters gonna hate...
On SUVs - Drive your B like a soccer mom is texting her friends about how she wants to kill you...
Red Betty - http://www.mgexp.com/registry/GHN5UH418165
Bart - http://www.mgexp.com/registry/GHD4U146898G

barry s Avatar
barry s Silver Member Barry Stoll
Alexandria, VA, USA   USA
1972 MG MGB GT
1974 MG MGB
1976 Triumph TR6
1980 MG MGB
I feel lazy so I din't read the link. IIRC on my '80 I simply wired the coil feed off the fuse box instead of the relay. Isn't it that simple?

rustbelt Silver Member Len Norris
Flushing, Michigan, USA   USA
1977 MG MGB "Speckled Hen"
Thanks Dan, I think I'm starting to get it. I've printed the wiring diagram and am learning as we go along.
I wanted to reprint your response into this message to make it easier for everyone, but I can't figure out how to accomplish that. Here are some questions/clarifications to your response that I have:

1) Regarding all green circuits working with the key. Some do and some don't if I'm correct by following the green line on the wiring diagram. The hazard lights and the turn signals are not working. Everything else is working.

2) The OP does have a toggle switch on the dash that controls the fans. If I understand correctly, your saying the 'fan wire' (solid brown) is OK where it is (on the bottom) if I'm OK with using the toggle, or I could move it up to the second circuit (your response says to move it to the bottom where it is currently) if I choose to eliminate the toggle? You also reference the wire to being 'brown white', while what's therecurrently is a solid brown wire. Would solid vs brown white make a difference?

3) Re: cutting the thinner gauge white w/ brown stripe from the second circuit and routing it to the relay, could I utilize the single white w/ brown stripe wire currently on the bottom circuit for that connection?

I sure appreciate your help, I obviously am not familiar with the electrical aspects of the car, but there is already several things I've learned so far in your responses. Thanks.

Nicecar Avatar
Nicecar Gary (ex "Harv") G
Victoria, BC, Canada   CAN
1980 MG MGB "Red On Red On Red"
Welcome.

To supplement your Advance wiring diagram, here are two more docs. that will come in handy.
---------

http://www.mgexp.com/article/lucas-colours.html

(Note that these colour codes may not apply directly to older cars. For example, the wipers on cars up to 1980 (at least) are not on a separate fuse circuit, so they are not orange, but green. Check the schematic for your car to be certain. - cak)

Based on a page by Chris Kantarjiev of The Dimebank Garage with several additions and modifications by Skye Nott.
----------
http://www.mgexp.com/phorum/read.php?1,2661168,2661310#msg-2661310
Ign. Switch Positions
---------

Why "Speckled Hen"?

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Ex-Calif Avatar
Ex-Calif Gold Member Dan D
Cincinnati, Ohio, USA   USA
1968 MG MGB GT "Bart - Yellow And Naughty"
1977 MG MGB "Red Betty"
2012 Jeep Liberty "Tank"
2014 Hyundai Accent "Skate"
To copy someone's text in your reply you can hit the "quote" button at the bottom of their message.

So to your queries. I am using your drawing above. Just to baseline here are the basic color codes for the MG

Brown - "Direct" from battery - no switches or fuses - always hot
White - "Direct" from the ignition switch - Switched power with no fuses - hot with key on
Green - Switched power that is fused - It is white across the fuse in the fuse box - hot with key on
Purple - Non-switched power that is fused - It is brown power across the fuse in the fuse box - Always hot

Brown wire on the bottom - this needs to stay put where it is. This is the wire that supplies the purple on the other side.
Brown/white on the bottom - this is the circuit I am referring to. This circuit is normally on the third pole with the other brown/whites. I susplect this is the original fan circuit - normally the fans would go off with the key. If OP put it on the bottom with brown then the fans would operate without the key being on.

If any green circuits are working then the other two brown/whites are correct - one of them brings power in from the ignition relay ("white" power) then across the fuse are the green circuits.

Your hazards and turns not working is another matter entirely.

A lot of guys add a toggle to manually control their fans. There are various ways to do that so I would not mess with things at this point as long as the fans are working.

For now - move the white/brown from the bottom to the third and take the thinner brown white from the double plug. You can cut this off close to the plug and route it to the white on the ignition relay. You may have to patch in a section of wire to make it reach.



The goal - Reliable summer driver interspersed with mechanical tinkering...
Motto - "Driving fifty in the twisties..."
On Mods - It's your damn car - Do what you want. Haters gonna hate...
On SUVs - Drive your B like a soccer mom is texting her friends about how she wants to kill you...
Red Betty - http://www.mgexp.com/registry/GHN5UH418165
Bart - http://www.mgexp.com/registry/GHD4U146898G

rustbelt Silver Member Len Norris
Flushing, Michigan, USA   USA
1977 MG MGB "Speckled Hen"
Thanks Dan, I understand what your saying now. I got hold of a basic auto wiring book and am starting to read it. I'll make the wiring change as soo as my new ignition relay and fuse block come in Abe report back on what happens.

Gary, 'Speckled Hen' came about because someone sprayed gold metal flake mixed in a clear coat and hence the name. Might rename after I remove the flake.
Len

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rustbelt Silver Member Len Norris
Flushing, Michigan, USA   USA
1977 MG MGB "Speckled Hen"
In reply to # 3591639 by Ex-Calif To copy someone's text in your reply you can hit the "quote" button at the bottom of their message.

So to your queries. I am using your drawing above. Just to baseline here are the basic color codes for the MG

Brown - "Direct" from battery - no switches or fuses - always hot
White - "Direct" from the ignition switch - Switched power with no fuses - hot with key on
Green - Switched power that is fused - It is white across the fuse in the fuse box - hot with key on
Purple - Non-switched power that is fused - It is brown power across the fuse in the fuse box - Always hot

Brown wire on the bottom - this needs to stay put where it is. This is the wire that supplies the purple on the other side.
Brown/white on the bottom - this is the circuit I am referring to. This circuit is normally on the third pole with the other brown/whites. I susplect this is the original fan circuit - normally the fans would go off with the key. If OP put it on the bottom with brown then the fans would operate without the key being on.

If any green circuits are working then the other two brown/whites are correct - one of them brings power in from the ignition relay ("white" power) then across the fuse are the green circuits.

Your hazards and turns not working is another matter entirely.

A lot of guys add a toggle to manually control their fans. There are various ways to do that so I would not mess with things at this point as long as the fans are working.

For now - move the white/brown from the bottom to the third and take the thinner brown white from the double plug. You can cut this off close to the plug and route it to the white on the ignition relay. You may have to patch in a section of wire to make it reach.

Installed my new fuse box and ignition relay switch today.
Disconnected the thin white/brown wire from the third circuit (second from the bottom) and connected it with the white/brown wire going into the front most terminal on the ignition relay (please refer to my drawing of the relay in the beginning post). The car continues to run after turning the key off.
I'm wondering now, since there actually is a solid white wire connected on the left side of the relay (prior drawing), if I should have tied into that on vs the white/brown wire?
Asking opinions first before I make the move and have to add additional wire length.
Thanks, Len

arnolda Arnold Adams
Vancouver, Washington, USA   USA
In reply to # 3591370 by rustbelt Have a few questions regarding the rewire advice found in the search section that cures the 'car keeps running after key is off and removed' issue. My 77B has the ignition switch relay, which I understand was a new feature in late 1977, but unfortunately, created the issue I am having. The cure appears to be a 5 minute job, requiring the moving the small white w/ brown stripe wire from the fuse box to the ignition switch relay next to it. The instructions are called: MGB Ignition System Feedback, found in a 5/17/11 post titled 'Car won't shut off'.

I think you are referring to the anti-runon circuit. This circuit starts at the ignition switch (slate) to an in-line fuse, then goes to the anti-runon valve solenoid (slate/pink) and then to an oil pressure switch (slate/yellow).

Ex-Calif Avatar
Ex-Calif Gold Member Dan D
Cincinnati, Ohio, USA   USA
1968 MG MGB GT "Bart - Yellow And Naughty"
1977 MG MGB "Red Betty"
2012 Jeep Liberty "Tank"
2014 Hyundai Accent "Skate"
Look at the schematic again - The white brown circuit on the relay in stock form goes "from" this relay to the fuse box.

By moving the brown/white to the brown/white you haven't changed things electrically. You've just connected white/brown in a different place.

The white circuit on the relay comes from the key switch. When the key is switched off the white circuit goes dead.

You need to attach the thin white/brown to the white on the relay.

The "sneaker" circuit on the 77 is in the white brown circuit. You need to isolate this white/brown ignition wire from teh white/brown circuit by attaching it on the white side.



The goal - Reliable summer driver interspersed with mechanical tinkering...
Motto - "Driving fifty in the twisties..."
On Mods - It's your damn car - Do what you want. Haters gonna hate...
On SUVs - Drive your B like a soccer mom is texting her friends about how she wants to kill you...
Red Betty - http://www.mgexp.com/registry/GHN5UH418165
Bart - http://www.mgexp.com/registry/GHD4U146898G

rustbelt Silver Member Len Norris
Flushing, Michigan, USA   USA
1977 MG MGB "Speckled Hen"
A huge thanks to all those who offered advice, especially Dan D who guided me through step by step on solving the issue that was unique to my 1977 that caused it to continue to run even after the key was off and removed. His advice of relocating a wire from the fuse box to the ignition relay solved my problem and now the car shuts off as it should. Thanks Dan for hanging in there with me.

Now it's onto getting the turn signals to work.
I'll do some research and reading. then start a new topic soon if necessary.
Thanks again.

Ex-Calif Avatar
Ex-Calif Gold Member Dan D
Cincinnati, Ohio, USA   USA
1968 MG MGB GT "Bart - Yellow And Naughty"
1977 MG MGB "Red Betty"
2012 Jeep Liberty "Tank"
2014 Hyundai Accent "Skate"
Glad you got it!

When you get under the dash for the turn signals, there will be a circuit up there with a diode in it. When this diode fails the starter will stay engaged when the parking brake is on.

I'll try and post a picture of the diode later...

It freaked me out when it happened to me (after a gas fill up) - Just remember this for future reference and definitely start a new thread on turns and hazards after reading up the hundreds of threads already done on it.



The goal - Reliable summer driver interspersed with mechanical tinkering...
Motto - "Driving fifty in the twisties..."
On Mods - It's your damn car - Do what you want. Haters gonna hate...
On SUVs - Drive your B like a soccer mom is texting her friends about how she wants to kill you...
Red Betty - http://www.mgexp.com/registry/GHN5UH418165
Bart - http://www.mgexp.com/registry/GHD4U146898G

. Hide banner ads & support this website by becoming a > Gold Supporting Member <

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