Wiring a Relay between ignition and starter

[courtenay]

I understand that putting a relay between the ignition switch and the starter reduces the "load" on the ignition switch. Does anyone have a diagram that would show how such a system would be wired?

[DieselSpider]

Hang a relay to the fender or firewall under the hood, take the wire activates the starter solenoid off the solenoid spade terminal and connect it to the positive side of the coil on the relay connecting the negative side to a ground, put an in line fuse holder on the input side of the contacts of the relay and wire that to the battery cable stud on the starter, run a wire from the output contact on the relay to the spade terminal on the starter solenoid that you removed the original wire from and then put a 30 amp fuse in the fuse holder and your done. Should take about 15 minutes if you have your wire, fuse holder/fuse, shrink wrap, relay, tools, fasteners and connectors already laid out when you start or 30 minutes if you stop for an iced tea or coffee.

[bradartigue]

You can also run the + side from the 30 terminal on the alternator...which is pretty much an extension of the loom from the starter lug. This gives you the advantage of being able to get to the wire/relay if necessary. If the alternator is on the driver's side that is; otherwise you'll have wire running side to side, which is ugly.

[DieselSpider]

On the Diesel the starter is on the right and quite accessible while the alternator is buried under the turbocharger plumbing and air filter on the drivers side.

[KevAndAndi]

Hang a relay to the fender or firewall under the hood, take the wire activates the starter solenoid off the solenoid spade terminal and connect it to the positive side of the coil on the relay connecting the negative side to a ground, put an in line fuse holder on the input side of the contacts of the relay and wire that to the battery cable stud on the starter, run a wire from the output contact on the relay to the spade terminal on the starter solenoid that you removed the original wire from and then put a 30 amp fuse in the fuse holder and your done. Should take about 15 minutes if you have your wire, fuse holder/fuse, shrink wrap, relay, tools, fasteners and connectors already laid out when you start or 30 minutes if you stop for an iced tea or coffee.

Bruce, I am also looking to install a starter relay. In order to visualize what DieselSpider is describing above, check out this link:

http://www.glenn-ring.com/tech/relay_starter.htm

It pertains to a VW bug, and the instructions describe a 5-pin relay, but the illustrations appear to depict a 4-pin relay. I believe that is what we would need. (Please someone correct me if I'm wrong.)

For Bruce's and my benefit, could someone confirm the following:

1) What type of relay should be used? Is it 4-pin? 30 amp? 40 amp?
2) What gauge wire should be used?
3) What type of fuse should be used? DieselSpider, above, recommends 30 amp, but I'm seeing recommendations on the interwebs for a 15 amp fuse. Why the difference in the recommendations?

Thanks.

[courtenay]

Thank you folks - very clear, although I am interested in seeing the answers to Kev's questions.
Bruce

[DieselSpider]

I use the 40 amp Optronics relay available at just about every parts store for about $5 and the standard weather sealed blade style fuse holder. A 30 amp fuse is to protect the 40 amp relay and wireing and allow for a high draw solenoid if you have upgraded to a higher torque starter. Most have a 750 watt starter so the solenoid probably will pull about 8 to 10 amps however the Diesel has over 2,000 watts and a high torque starter for a gasoline engine will be somewhere in-between so the solenoids can draw over 15 amps to hold the starter drive engaged against the flywheel ring gear against the greater torque of the starter motor.

Its not rocket science and going a little beefier there is going to ensure that you are not using a fuse that is on the cuspice limiting current to the solenoid and contributing to its premature failure.

These will do however if you can find a similar fuse holder with 10 gauge wires it would be better.


http://shop.advanceautoparts.com/p/optr ... ics+relay#


http://shop.advanceautoparts.com/p/buss ... use+holder

[KevAndAndi]

Thanks very much, Diesel.

I bought #10 wire to do the Brown Wire Fix and later discovered that my car already had the Fix. Sounds like I can use that wire for the starter relay fix.

One more question: Can the ground from the relay go to the fender ground pod (using a female spade connector), or should it go to an engine ground (with a ring connector)?

[spider2081]

Here is a drawing I put together of the relay I installed in my 1981 Spider 2000. I used #12 wire and although the drawing does not show it I used a 20 amp fues between the alternator output and the relay.




Sorry can't get diagram to show. Then I tried to delete this post and couldn't figure out how to do that either. I think I will go work on my car. No better I just mow the lawn.

[DieselSpider]

Thanks very much, Diesel.

I bought #10 wire to do the Brown Wire Fix and later discovered that my car already had the Fix. Sounds like I can use that wire for the starter relay fix.

One more question: Can the ground from the relay go to the fender ground pod (using a female spade connector), or should it go to an engine ground (with a ring connector)?

Ground pod worked just fine on mine.

[KevAndAndi]

Futzed around awhile last night in the garage figuring out how I might approach this. The only obstacle was that the crankcase ventilation hose is in the way and it makes it even more difficult to get the big boot off the starter solenoid. Therefore, I couldn't see what size ring connector I would need for the battery stud.

I need to change the ventilation hose anyway, so maybe I'll remove that, and the vapor oil separator, and replace the gasket, and replace the Little Elbow From HellTM...

This is how Project Creep happens.

[spider2081]

The only obstacle was that the crankcase ventilation hose is in the way and it makes it even more difficult to get the big boot off the starter solenoid.

This is why many folks use the output post on the alternator if it is mounted on the driver's side. The alternator output post and the starters battery terminal are electrically the same point. Also right behind the alternator are 2 single bullet connector one has red wires and one is brown brown wires. The red wire is the wire between the ignition switch and starter solenoid. Separate the bullets pull the end that is against the fender well up toward the grounding pod. It usually is long enough to attach directly to the new relay coil terminal. You will need to add a wire to go from the relay contact terminal to the solenoid spade.

[courtenay]

The only obstacle was that the crankcase ventilation hose is in the way and it makes it even more difficult to get the big boot off the starter solenoid.

This is why many folks use the output post on the alternator if it is mounted on the driver's side. The alternator output post and the starters battery terminal are electrically the same point. Also right behind the alternator are 2 single bullet connector one has red wires and one is brown brown wires. The red wire is the wire between the ignition switch and starter solenoid. Separate the bullets pull the end that is against the fender well up toward the grounding pod. It usually is long enough to attach directly to the new relay coil terminal. You will need to add a wire to go from the relay contact terminal to the solenoid spade.

Great suggestion! Rather than connecting a wire between the relay contact and the solenoid terminal, I assume you could connect the wire between the relay contact and the other end of the red wire disconnected behind the alternator.

[KevAndAndi]

The only obstacle was that the crankcase ventilation hose is in the way and it makes it even more difficult to get the big boot off the starter solenoid.

This is why many folks use the output post on the alternator if it is mounted on the driver's side. The alternator output post and the starters battery terminal are electrically the same point. Also right behind the alternator are 2 single bullet connector one has red wires and one is brown brown wires. The red wire is the wire between the ignition switch and starter solenoid. Separate the bullets pull the end that is against the fender well up toward the grounding pod. It usually is long enough to attach directly to the new relay coil terminal. You will need to add a wire to go from the relay contact terminal to the solenoid spade.

Ah. Duh. Yes. Alternator post it is. Thanks!

It occurred to me that I could tap into the ignition wire using two wires, each with a female spade connector on one end (for the relay) and a bullet connector (one male, one female) on the other. This would make the wiring easily reversible, like Greg Smith's headlight relay kit.

[spider2081]

It occurred to me that I could tap into the ignition wire using two wires, each with a female spade connector on one end (for the relay) and a bullet connector (one male, one female) on the other. This would make the wiring easily reversible, like Greg Smith's headlight relay kit.

I prefer to eliminate the bullet connectors entirely, They are often corroded and part of the "click" problem. I cut off the one on the wire from the ignition switch and crimp on the female spade for the relay. I don't use the relay socket. the wire goes directly onto the relay. I don't use the wire from the bullet to the starter solenoid rather I add a new wire from the relay to the starter solenoid with two new female spade connectors on it. I tie back the unused wire and tape the ends over to avoid confusion. This way everything in the relay circuit is new.