Section : Electrical Equipment

Alternators, dynamos, lights, wipers, etc.

Starter Relay ("solenoid") wiring

Posted By : Adrian Lester, 25-Apr-2004, 08:15pm

Vehicle: Spitfire 1500, 1981.

Symptom: The car does not start, the starter motor does not turn when the key is turned.

Further info: Shorting accross the two major connections on the starter relay (battery +ve to relay and relay to motor) causes the motor to turn.

Investigation required: I need to find out whether the problem is with the starter relay itself or is upstream of that. I need to assess this quickly in order to have the car back in action for Wednesday.

Confusion: I have four wires on the relay: the battery + to relay, relay to starter and two thin ones. The thin ones are one red and white, and one yellow and white. Reading the archives here it would appear that the yellow and white is a bypass of the ballast resistor. What's the red and white one? Does it connect to earth/something else when the key is turned?

Can someone tell me what voltages / continuity changes I should get between these wires when I turn the key (and when it is not turned)? At the moment it seems pretty random if anything but I don't know what I'm looking for.

Also, I understand earlier starter relays to incorporate a test switch but not support the ballast resistor bypass. Is it possible to get a relay for the 1500 with a test switch and ballast resistor bypass connection on it? If so would the test switch suffice to start the car? As you may have gathered I rather need to get this thing going again!

Many thanks in advance,

Adrian
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Followups :

Starter Relay ("solenoid") wiring

Posted By : James Carruthers, 25-Apr-2004, 08:21pm

Adrian,

Mine did *exactly* the same thing as yours is doing...

Turned out that the main positive battery cable going to the solenoid was broke - though I tested it with a multimeter and everything was fine - visually it look good too.

To test this you could run a jump lead from the positive battery terminal to the solenoid - basically doubling up the (normally red) cable...

James
- Starter Relay ("solenoid") wiring
  
  Posted By : Ben Ferguson, 26-Apr-2004, 09:07am
  
  Mine had this problem also, and it was the solenoid sticking, fairly commmon problem I think. If the solenoid makes a farily quiet thud wihtout doing anything or makes no noise at all, I'd suspect the wiring to the ignition barrel and back was at fault (low tension side of things) If still no joy like James suggested to me at the time use a jump lead as an HT lead and see if the fault lies in a broken cable.
  I dont know anything about different types of solenoid unfortunately, other than they are cheap; I got a shop-soiled one recently from Bill at rarebits for something like &163;7, solved all my problems
  
  Ben
  - Starter Relay ("solenoid") wiring
    
    Posted By : Adrian Lester, 26-Apr-2004, 10:18am
    
    Thanks for the advice there, but I just went out to try it, put the key in and turned it ...... and the car started. I can't fix the problem while it's not there so I reckon I'll have to wait until next time it dies (probably in the dark in the back of beyond with pooring rain and a batallion of angry paras after me following a bar fight .....).
    
    When that happens is there any particular reason I shouldn't start the car by connecting the two major terminals on the solenoid together with jump leads?
    
    Adrian.
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    - Starter Relay ("solenoid") wiring
      
      Posted By : Paul Bodiam, 26-Apr-2004, 02:22pm
      
      Hi Adrian
      
      You wrote: "When that happens is there any particular reason I shouldn't start the car by connecting the two major terminals on the solenoid together with jump leads?"
      
      Be careful: if you connect a jump lead to the battery +ve terminal or to the battery side of the solenoid, and then accidentally touch the other end on any earthed part of the engine or unpainted body fixing, you run the risk of spot-welding the jump lead in place and/or starting a fire. With no resistance in the way, a jump lead can pass an *enormous* current.
      A safer way is to use an old ring-spanner to bridge the gap between the bolt-heads on the solenoid.
      
      cheers
      Paul
      - Temperature dependent Starter Relay?
        
        Posted By : Adrian Lester, 27-Apr-2004, 05:42pm
        
        Well, the problem seems to be intermittent and having put a multimeter on things when it was working I have deduced that when it does not no +ve voltage is being applied to the red and white wire as it should be.
        
        With the exception of one time the system has failed after recently running the car. If I let the car stand for a while and come back then everything seems to work. The one assumption was on Sunday when the car was parked in direct sunlight. Hence the only thing I can think is that this is a temperature dependent problem.
        
        Now the wiring diagram shows that the red and white wire attaches to the ignition switch only, has anyone any idea what might be going on or what I should do about it?
        
        Many thanks again,
        
        Adrian.
        
        Temperature dependent Starter Relay?
        
        Posted By : Chris Wilson, 27-Apr-2004, 06:38pm
        
        Hi Adrian,
        
        I'm not sure if I'm going to be of any help or add to the confusion. I had a problem with the starting of my 1975 1500 last year or the year before. Not sure if it was the same symptoms as you are suffering but I finally traced it to a knackered ignition switch!! (The white bit that fits behind the ignition switch etc - not sure how it features in the later models!). I bought a new "white bit" complete with wires etc, fitted it and problem was resolved!) BTW - the red/white wire is the feed from the ignition switch and if this is faulty or intermittent, this could be the cause of your problems? The Haynes Classic Car Electrical Systems repair manual has some basic fault finding instructions regarding starter motors if you can get hold of a copy?
        
        Regards
        
        Temperature dependent Starter Relay?
        
        Posted By : Michael Rantell, 27-Apr-2004, 08:08pm
        
        Adrian,
        I have the exact same problem on my mk3 GT6. On the hottest days last summer if I parked up at a petrol station for example, on trying to re-start no solenoid - nout - nothing . Leave a couple of minutes and everythings fine. I did some diagnosis and convinced myself it was the solenoid but since the summer's gone I've not had the problem since so I've done nothing.
        
        I'm waiting to see if the problem returns ...
        
        regards,
        
        Mike
        
        Temperature dependent Starter Relay?
        
        Posted By : Paul Bodiam, 27-Apr-2004, 11:46pm
        
        Hi Adrian
        
        If the red and white wire does not have +12v on it when the key is turned to the "start" position, then the problem is not with the solenoid at all, but further up stream. The most likely candidate is the ignition switch itself.
        
        You can remove just the switch part from the back of the ignition barrel by taking the cowling off the steering column and then releasing the grub-screw that holds the switch into the barrel. You can then disconnect it from the loom at its connector and test it with a multimeter. In the "start" position, all four wires coming out of the switch should be connected together (as shown on a multimeter).
        
        If you need to replace the switch, it is part number 218959 (Canley: &163;17.06, Rimmer: &194;&163;29.96)
        
        hope this helps
        
        Paul