Starter motor relay install
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Thread: Starter motor relay install

  1. #1
    Fellow Frogger! Bluey's Avatar
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    Default Starter motor relay install

    Many French cars trigger the starter solenoid directly off the ignition barrel. The contact can burn out over time and no amount of linishing will make if function properly again. Common behaviours of a burnt out contact include a click and no turning of the motor or a click, pause, motor turns. The solution is to install a starter relay to take the load off the barrel.

    Parts Required
    Relay
    Bosch 12V 40A - 0 332 019 151 Ė $14.70 BOSCH 40 AMP RELAY - GR Motorsport Electrics
    Narva 12V 40A Ė 68028BL Ė $17.50 (Repco, Auto One, Burson, Peps, etc)

    Relay holder
    Bosch Ė 3 334 485 008 - $6.50 RELAY HOLDER - GR Motorsport Electrics
    Narva Ė 68084BL - $8.80

    8mm ring terminals (2 max.) for +12V terminal & earth
    5mm/6mm ring terminals (2 max.) for solenoid terminal & earth
    1 wire connector x1 to connect original solenoid wire. (Blister pack) Narva: 56271BL - $8.95
    Black 3mm wire Ė $6.95
    Red 4mm wire - $6.95
    M8 or M6 bolt for earth depending on what
    Wet & dry/Scotchbrite (to clean earth point)
    Crimping tools (Jaycar TH-1834 for the relay terminals)
    Wire stripper
    Nuts, bolts & washers to fasten relay holder Ė M5 or M6





    The install is easiest when the relay is located as close to the starter as possible. Disconnect the battery. Strip back whatever components you need to access the starter. When laying the wiring, work from the terminals & connector towards the relay

    Mount the relay & holder

    Find a suitable earth point on the engine block or gearbox. Crimp a matching ring terminal to black wire, attach and run the wire back to the relay.

    Crimp ring terminals to red wires to attach to the +12V & solenoid terminals on the starter and attach.

    Snip the original solenoid wire (trigger) in a suitable place, crimp one of the connector terminals and fit the housing. Crimp the other connector terminal to another piece of wire and fit the corresponding housing.

    Group all 4 wires together at the relay and snip them 10mm longer than the bottom edge of the relay holder. Crimp all 4 relay terminals and clip them into the relay holder as follows

    30: +12V
    85: Earth
    86: Trigger
    87: Solenoid





    I prefer to encase wiring in heat shrink. This should be done before fitting the relay terminals. Convoluted tube or electrical tape is fine too and can be fitted at any time.



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    Reassemble engine bay. Reconnect the battery and test.
    Beano, JohnW, bowie and 4 others like this.

  2. #2
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    That's the way to do it, did almost exactly the same, I mounted the relay under that tray to keep it well out of sight and very short leads.

    Love your thinking, gave me a chuckle remembering I did just this about 8 months back. as I was stuffing around with this jig saw puzzle I have.
    87 S1 205 GTI / GTI6 powered a project underway

  3. #3
    1000+ Posts robmac's Avatar
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    I'm surprised you didn't fuse the cable off the battery lead. Any short on this, or the other load circuit will result in big melt down.

    However it's not very likely for cabling to shot, however relays do fail internally.

    Edit:
    Perhaps the relay has an inbuilt load circuit fuse ?

    In which case I apologize.
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  4. #4
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    I think / hope I used an inline blade fuse actually, I remember thinking how much does a started solenoid pull!
    87 S1 205 GTI / GTI6 powered a project underway

  5. #5
    1000+ Posts robmac's Avatar
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    Quote Originally Posted by Matthew View Post
    I think / hope I used an inline blade fuse actually, I remember thinking how much does a started solenoid pull!
    The starter solenoid current is largely irrelevant.

    The fuse is there to limit the current from the main battery lead if something goes awry.

    Any fuse from 10 -30 amps will do the job equally well.

    Lead acid accumulators have very low internal resistance and are capable of supplying several hundred amps into a direct or partial short.
    Mutual Respect is Contagious


  6. #6
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    Yes I know that, the thought was 20A in series with supply. Given supply fed the relay and powered the solenoid I seem to remember 20A was used, will check but its very hard to see in there now! Not much more of a risk really the solid cable going to solenoid and alternator from battery is not fused. Battery is measured as admittance if I remember that correctly! Communications was / is my game. Filling with cars is a hobby / necessity! Good ideas like this only occasionally!
    87 S1 205 GTI / GTI6 powered a project underway

  7. #7
    1000+ Posts robmac's Avatar
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    With any low resistance current source one has to consider the failure mode & a method of mitigating the damage if any.

    Those with formal qualifications have no excuse and are obligated to point out design oversights to others.
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  8. #8
    1000+ Posts BIGRR's Avatar
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    Give it to those young blokes Rob!

    Wish I had formal qualifications.

    I only have a 1.75lb hammer.
    Present fleet:-
    Peugeot 93' 205 Gti 16v
    Peugeot 73' 504 Ti from new
    Peugeot 08' 407 Hdi Coupe from new

    Previous fleet:-
    Peugeot 95' 605 Sv
    Peugeot 92' 205 Gti
    Renault 72' 16TS from new
    Renault 69' 10
    Renault 71' 10s
    Renault 68' 10 from new

    "Be reasonable do it my way!"


  9. #9
    Too many posts! JohnW's Avatar
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    Nice and thanks. I like the "supercrimp II" tool!
    JohnW

    Renault 4CV 1951
    Renault R8 1965
    Renault Scenic 2005 (wife's)
    Renault Scenic 2007 (mine)
    Peugeot 306 XT 1995 (daughter's)
    CitroŽn CX Pallas 1980

    National Co-ordinator, Renault 4CV Register of Australia

  10. #10
    1000+ Posts PeterT's Avatar
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    Just don't bury the relay too deep, otherwise heat will effect it's functionality. You definitely don't want it under a 205 or 405 manifold.
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  11. #11
    1000+ Posts robmac's Avatar
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    Formal is another way to say "the school of hard knocks". After gaining some understanding of the fundamental principles.

    That withstanding I have a bit of paper on the wall, which cost me few years of my life to gain. And it began the process of learning.

    So please excuse me for putting that learning into a practical form and giving advice.

    I too had the use for a hammer, it drove the nail that hangs the piece of paper.
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  12. #12
    Fellow Frogger! CEyssens's Avatar
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    Thanks for sharing this it will help lots improve this weak point.
    I definitely agree with location being important, under the manifold looks a bit hard to access.

  13. #13
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    Icon14 Pat on the back for you Bluey! well presented article!

    Bluey

    Thanks for the way you set about this task and the effort you made to clearly describe and depict how you went about it, including the install on the vehicle. Wonderful work, that can be followed by all, (including the buy list) as I am sure that others will come across similar problems that require the addition of a new relay to improve on the circuits of our older cars, well done.

    A very helpful post!

    Regards

    Ken

  14. #14
    Too many posts! JohnW's Avatar
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    I really like that crimping tool and found the excellent Bellanco website - thanks for that information alone! Do you have a second crimper for push-on terminals fitted with an insulating sleeve?

    By the way, I'm sure it isn't only French cars - until relatively recently few cars had any relays. What's relative - I suppose 20-30 years. Certainly the old Nieman devices on Renaults didn't seem prone to any trouble except eventual wear of the mechanical parts.
    JohnW

    Renault 4CV 1951
    Renault R8 1965
    Renault Scenic 2005 (wife's)
    Renault Scenic 2007 (mine)
    Peugeot 306 XT 1995 (daughter's)
    CitroŽn CX Pallas 1980

    National Co-ordinator, Renault 4CV Register of Australia

  15. #15
    Fellow Frogger! Bluey's Avatar
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    Quote Originally Posted by robmac View Post
    I'm surprised you didn't fuse the cable off the battery lead. Any short on this, or the other load circuit will result in big melt down.
    Fitting a fuse would make it infallible. I'll add one in on the next install and update the pics.
    I didn't consider it as I had zero rub through issues and there would have to be both an internal short inside the solenoid or starter and a faulty relay jamming the contact shut or an idiot hanging off the key for a long period.

    Quote Originally Posted by JohnW View Post
    I really like that crimping tool and found the excellent Bellanco website - thanks for that information alone! Do you have a second crimper for push-on terminals fitted with an insulating sleeve?
    I prefer the Super Crimp on insulated terminals and the Duratech crimp (below the pivot) for non-insulated. At a pinch you can strip wire as small as 24AWG. They're robust and can take a lot of abuse, (ask my colleague ).

    The Duratech tool is superb for those curl over crimps. You can start off with the largest crimp and work your way down. I've used it on everything from 12AWG to 24AWG. They're $14.95.
    JohnW likes this.

  16. #16
    1000+ Posts robmac's Avatar
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    Quote Originally Posted by Bluey View Post
    Fitting a fuse would make it infallible. I'll add one in on the next install and update the pics.
    I didn't consider it as I had zero rub through issues and there would have to be both an internal short inside the solenoid or starter and a faulty relay jamming the contact shut or an idiot hanging off the key for a long period.
    Simply use a relay with an inbuilt fuse

    Starter motor relay install-fused-relay.jpg
    Mutual Respect is Contagious


  17. #17
    Fellow Frogger! blahblah's Avatar
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    Measure the resistance of the solenoid and use ohms law to calculate the current draw e.g Assume 13.5v with a 1ohm solenoid = 13.5A so make it 15A.
    I did this mod and got caught - assumed a 15A fuse would be more than enough which it did for over a month. So when the car wouldnít start I didnít think about the fuse! The solenoid was 0.9 ohms so 13.5v / 0.9ohms = 15A. Put in a 20A fuse and itís been fine ever since....


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  18. #18
    Too many posts! JohnW's Avatar
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    Quote Originally Posted by blahblah View Post
    Measure the resistance of the solenoid and use ohms law to calculate the current draw e.g Assume 13.5v with a 1ohm solenoid = 13.5A so make it 15A. I did this mod and got caught - assumed a 15A fuse would be more than enough which it did for over a month. So when the car wouldn’t start I didn’t think about the fuse! The solenoid was 0.9 ohms so 13.5v / 0.9ohms = 15A. Put in a 20A fuse and it’s been fine ever since.... Sent from my iPhone using Tapatalk
    No wonder the ignition switches get a work out!! Still, they are big solenoids.... I'll be out with the meter this morning!
    JohnW

    Renault 4CV 1951
    Renault R8 1965
    Renault Scenic 2005 (wife's)
    Renault Scenic 2007 (mine)
    Peugeot 306 XT 1995 (daughter's)
    CitroŽn CX Pallas 1980

    National Co-ordinator, Renault 4CV Register of Australia

  19. #19
    1000+ Posts robmac's Avatar
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    Quote Originally Posted by JohnW View Post
    No wonder the ignition switches get a work out!! Still, they are big solenoids.... I'll be out with the meter this morning!
    The reason any contacts switching the starter solenoid get a work out is because the solenoid coil, by design is highly inductive.

    When the contacts are opened the back Emf from the coil appears across the contacts.

    The best technical solutions are a reverse biassed diode across the solenoid coil or even a quench capacitor across the contacts.

    However , I suspect , for cost,reliability and historic reasons manufacturers don't use any back emf suppression device.
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  20. #20
    Too many posts! JohnW's Avatar
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    So, the right spec. diode from the activating wire terminal at the starter solenoid to earth is a good idea? Sounds like cheap insurance, doesn't it, for those aging ignition switches? Or for a new relay for that matter?

    Interesting as usual, thanks!
    JohnW

    Renault 4CV 1951
    Renault R8 1965
    Renault Scenic 2005 (wife's)
    Renault Scenic 2007 (mine)
    Peugeot 306 XT 1995 (daughter's)
    CitroŽn CX Pallas 1980

    National Co-ordinator, Renault 4CV Register of Australia

  21. #21
    1000+ Posts robmac's Avatar
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    I've be suggesting a BIG diode. A few amps at 1000v Piv.

    Something like this
    https://www.jaycar.com.au/diode-1n54...k-100/p/ZR1017

    And maybe put 3.3 ohm 5 watt resistor in with the series with the diode to limit the current.

    The diode needs to be reverse biassed when power is applied to the solenoid.
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  22. #22
    1000+ Posts driven's Avatar
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    Good explanation of why relay is great value in link

    Mounting of relay diode as per Fig 6

    http://www.aeroelectric.com/articles/strtctr.pdf
    JohnW likes this.

  23. #23
    Fellow Frogger! TassieExec's Avatar
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    Hi Bluey
    Thanks for a well set out and very advisable modification to the staring circuit, however it may be helpful to clarify something which may alleviate some concerns that have been raised, you don't need to stress about how close the relay is to the solenoid because the current draw or load takes place across the entire length of the cable from battery positive through the relay to the solenoid. Therefore just use the shortest overall length of 4 to 6mm2 cable depending on distance of the solenoid from the battery and place the relay in the most practical place. While we are on the subject it is also a very helpful modification to fit a relay to the headlights, this will greatly extend the life of the headlight switch and ensure you that you actually get 12volts under load at the headlights.
    Regards
    Neil

  24. #24
    1000+ Posts schlitzaugen's Avatar
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    Headlights do have relays from factory on the 205GTI. The problem with getting less than 12V (pretty much anywhere on these cars) has more to do with corroded (by now) ground contacts. Other manufacturers have found a better solution than Peugeot and have used service ground wires directly to the consumer.

    Rob's idea with the diode is taking it to the next level (and the current limiting resistor is the next level in anal retentive OCD, hehehehe). I wouldn't worry about spikes in voltage after all it's just a relay to the starter. If it were controlling some electronics such as a PWM DC motor ESC I would, but then I would suggest a Schottky. Voltage spikes are greater across the motor terminals but how long does that spin? And what is powered/can be affected during that time?
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