Wiring diagram hard start relay (problem...)

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Joost van der Velden
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Wiring diagram hard start relay (problem...)

#1 Post by Joost van der Velden »

Hello,

I would like to install a hard start relay on my starter. To get one all the way from the USA is expensive. Therefor I bought a Bosch relay myself.

Can some help with how to wire the relay to the starter?

Many thanks
Joost
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Last edited by Joost van der Velden on Tue Feb 13, 2018 5:54 pm, edited 1 time in total.
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Hugo Karasawa
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Re: Wiring diagram hard start relay

#2 Post by Hugo Karasawa »

In the mean time this will help, I have seen two ways of doing it, one with the relay behind the dash and one with the relay close to the starter motor.
https://www.youtube.com/watch?v=Kb7DAyXMMfQ&t=518s

viewtopic.php?f=4&t=40763

E Rutherford
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Re: Wiring diagram hard start relay

#3 Post by E Rutherford »

The most effective location for the relay is at the starter. The typical starter relay has the following terminals.

85 = controls the coil, can be either the ground or 6 volts
86 = controls the coil, same as above, just the opposite of what 85 is configured at
30 = Power source (Battery) for supplying the device on either 87 or 87a
87 = This would control the solenoid.
87a = Blank

Annie's video isn't bad to watch to get an idea of what is involved.

ed
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David Jones
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Re: Wiring diagram hard start relay

#4 Post by David Jones »

Ed, all mine are installed under the dash. Why would you install it at the starter if it is only there mainly to save the ignition switch from a high load and reduce the volts drop across the switch. Do you think there will be less volt drop by installing it at the starter?
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Greg Bryan
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Re: Wiring diagram hard start relay

#5 Post by Greg Bryan »

Here's a diagram ...
Starter with relay.png
Wire it as per Ed's terminal call-outs above.
Good luck!
Greg Bryan

E Rutherford
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Re: Wiring diagram hard start relay

#6 Post by E Rutherford »

David it puts the load closest to the source, battery + Starter. The ignition switch is only activating the coil in the relay which is minimal.

ed
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Hugo Karasawa
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Re: Wiring diagram hard start relay

#7 Post by Hugo Karasawa »


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Joost van der Velden
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Re: Wiring diagram hard start relay

#8 Post by Joost van der Velden »

Thanks all for the replies!
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Joost van der Velden
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Re: Wiring diagram hard start relay

#9 Post by Joost van der Velden »

Hello,

I did install the relay but when starting nothing happens. When I remove the relay the car starts. Please see the picture:

The brown wire is 86
The blue wire is 87
The black wire to the solenoid is 30
The black wire that goes out of the picture goes to the wire that was attached to where to blue wire is now attached to (nr 85)

What could be wrong?
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Hugo Karasawa
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Re: Wiring diagram hard start relay (problem...)

#10 Post by Hugo Karasawa »

Bench test the relay. Is it working ?

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Al Zim
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Re: Wiring diagram hard start relay (problem...)

#11 Post by Al Zim »

Putting in a relay is not the correct way to solve your electrical situations. Careful cleaning of the interior of the stater bu removing the end cap and blowing compressed air through the starter in many instances will cure your situation. This also gives you the opportunity to examine the brushes in the starter. Checking the resistance of the ground wire and the first foot of the starter wire (as previously outlined) will probably yield interesting results. With an ohm meter (purchase a good one) check resistance in your wiring. Remove the resistance and you will probably not need a relay. These cars functioned for years without added electrical components they should still do so with some loving care. al zim
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Hugo Karasawa
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Re: Wiring diagram hard start relay (problem...)

#12 Post by Hugo Karasawa »

I assume you are connecting the battery positive cable to where the large black cable 30 is connected.

E Rutherford
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Re: Wiring diagram hard start relay (problem...)

#13 Post by E Rutherford »

Joost,
Here is a part of the instructions that comes with the relay kit. Send me a PM and I'll email you the entire pdf.

Pull the #50 (black wire) quick disconnect terminal from the solenoid & connect to the #86 terminal (bare) on the relay.
The black wire with the quick disconnect terminal at the relay (#87) connect on the just vacated terminal #50 of the solenoid.
Now loosen the nut on the solenoid holding the heavy battery cable.
Land the “big gray” wire from the relay (#30) on this stud. Check all connections, screws tight.
Connect the battery ground strap.

Yes it is true that the systems have worked for years, but the relay makes life easier for the starting system.

You can use a box wrench to remove a nut, but using a ratchet box wrench makes life easier. :wink:

ed
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Joost van der Velden
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Re: Wiring diagram hard start relay (problem...)

#14 Post by Joost van der Velden »

Problem solved. Thanks to all!
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Hugo Karasawa
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Re: Wiring diagram hard start relay (problem...)

#15 Post by Hugo Karasawa »

What was the problem ?
Relay, bad connection, ground ?

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