locating starter-motor wiring?

Heya guys,

Looking for a bit of help I cant get myself right under the car atm as I don't have a jack an axle stands! Trying to locate the wiring for the starter motor and I think I've found it and would like to put an image here to see if anyone else could tell me if it is.

I have to say it's the only + wire going down the back of the engine and in the direction of the starter-motor, I am wondering if the wire is even large enough to carry the current to fully push the starter! looks to be like any other wire in the engine bay but with some kind of protective jacket around it.



I thought wire with the same awg that was used on car batteries was used more then this sort of size?
Also is the - going to the chassis, engine? I assume it is and it's well out of sight.

Any thoughts on this, most welcome
Kind regards,
Didge

Probably worth mentioning you have an auto?

I can't remember the routing of the starter motor wires on an auto, but I think you'll need to get underneath it to check it out properly.

Are you sure its not the shift interlock?

paul_c said

Probably worth mentioning you have an auto?

I can't remember the routing of the starter motor wires on an auto, but I think you'll need to get underneath it to check it out properly.

Are you sure its not the shift interlock?

Are you sure its not the shift interlock? not 100% sure what you mean but I assume you mean the gear lever and I have to say it's does it when I run the car around for a few hours and then pull-up and shift into P(park?) After that it's dead as roadkill. It's only once died in traffic but that was with the original engine(before the swap)

This shift interlock, are you saying their maybe some kind of connection that is either loose or just broken and giving the engine a faulty signal to kill the engine?

EDIT: bit confused, now are you saying the wire in the photo could be to the shift interlock?


Sorry yeah mate, it's an auto ;S

I'm lost mate, sorry..

I've got so many small issues with the wiring and firing of the engine I can't remember which post I'm on. half-sharp this evening mate

Have a look at the wiring diagram, on an auto there is a shift interlock which prevents STARTING (not RUNNING) in any gear except park or neutral. If this were faulty, it might not send any electricity to the starter - hence the need to check the wiring properly, ie by using a voltmeter on the starter solenoid terminal.

Also, I don't think its your starter, you mention you can hear a relay click. Is it a loud click from the engine bay or a quiet click from the fusebox area? A loud click might be the starter solenoid, a small one a relay. Again, voltmeter test would tell you which it is.

paul_c said

Have a look at the wiring diagram, on an auto there is a shift interlock which prevents STARTING (not RUNNING) in any gear except park or neutral. If this were faulty, it might not send any electricity to the starter - hence the need to check the wiring properly, ie by using a voltmeter on the starter solenoid terminal.

Also, I don't think its your starter, you mention you can hear a relay click. Is it a loud click from the engine bay or a quiet click from the fusebox area? A loud click might be the starter solenoid, a small one a relay. Again, voltmeter test would tell you which it is.

Cheers Paul

I'm pretty sure the click is coming from the relay on the fuseboard it seems to be emanating from that direction, (when in the drivers seat it seems far left it's not loud) and I now assume the starter-motor to be almost in-front but slightly right of the drivers seat(in the engine bay)

Right, I'll get a volt meter on it but as it only happens after I run the car around after a few hours how would I fix this when it does happen?

Is it a case of waiting for it to happen, then taking a volt meter out, checking the solenoid if no power getting to it. move the shifter about and try starting again when I get a voltage output?
So this could be down to a slipping gear-shifter or some wiring connecting the shifter to the relay and then switching power to the starter-motor.

You could rig up a little wire from the starter motor solenoid to a convenient point inside the car or in the engine bay; and when it fails, check this instead of having to crawl underneath the car. (Do an earth too).

The X relay clicks when you turn the key from run (ignition on position) to start, so this is normal. The starter motor not turning isn't though!

AFAIK there is already a heat shield for an auto starter motor.

paul_c said

You could rig up a little wire from the starter motor solenoid to a convenient point inside the car or in the engine bay; and when it fails, check this instead of having to crawl underneath the car. (Do an earth too).

The X relay clicks when you turn the key from run (ignition on position) to start, so this is normal. The starter motor not turning isn't though!

AFAIK there is already a heat shield for an auto starter motor.

hehe, yeah I've al'ready a few of them rig-up wires atm. all for other bits like the dash lights an stuff when people wonder passed with me in the car playing with wires they have a good look and think I'm mad.. so that's nothing new.. lol they should stop gossiping an get on with their own (little) lives, I could point out a few things their blind too which would raise some pulses quick

LOL looks a mess, but it works innit

Thanks for the damn spot-on help paul, I'll get onto that one tomorrow afternoon

that plug there is for the starter motor trigger yes, looks like someone has had a problem in the past and had to crimp a new spade on it. red/black wire is the starter trigger, black wire is either 5th injector trigger for fuel injection (unlikely if its auto) or coil power feed which gives it a boost when cranking. If i were you I'd take a closer look here, I've found most wiring work done by a PO is ends up being right bodge

the power for the starter comes from the battery +ve though, the red/black wire is just for the solonoid trigger. i have read that auto guys fit a relay on the solonoid wire to help with stuck starters due to heat soak, since the auto starter is on the back they suffer more from this problem.

to test if the starter i ok jump a wire from the battery + to the spade on the starter where the red/black wire is, if there are 2 spades the one you want is labled 50. if it cranks over you know the problem is the wiring, ign switch or the auto interlock gubbins. you can rule out the ign switch by takign the plug off it and bridge the red wire to the red/black, if it cranks over its the ign switch

rubjonny said

that plug there is for the starter motor trigger yes, looks like someone has had a problem in the past and had to crimp a new spade on it. red/black wire is the starter trigger, black wire is either 5th injector trigger for fuel injection (unlikely if its auto) or coil power feed which gives it a boost when cranking. If i were you I'd take a closer look here, I've found most wiring work done by a PO is ends up being right bodge

the power for the starter comes from the battery +ve though, the red/black wire is just for the solonoid trigger. i have read that auto guys fit a relay on the solonoid wire to help with stuck starters due to heat soak, since the auto starter is on the back they suffer more from this problem.

to test if the starter i ok jump a wire from the battery + to the spade on the starter where the red/black wire is, if there are 2 spades the one you want is labled 50. if it cranks over you know the problem is the wiring, ign switch or the auto interlock gubbins. you can rule out the ign switch by takign the plug off it and bridge the red wire to the red/black, if it cranks over its the ign switch

Heya rub,

I've got a relay about as it happens it looks like this:


Not trying to sound any simpler then I am, but I assume this should be okay to wire into the circuit, just take the connection out of the socket, add this in along with a wire leading to my battery and jobs a gooden?

When the ign swich is thrown, it will always take power straight from the battery via the relay, right?
Just I'm not 100% sure which legs to wire up where if you get me.. ;D

Kind regards,
Didge.

P.S: not been out to test anything yet, it's so snowy, cold and icky with the cover on the car I've not been near 'er

I've got a funny idea in my head about this, wiring it up as it were..

When current is passed through the red/black wire connected to post 86 on the relay then out post 85 back through the red/black wire which leads to the solenoid on the starter motor this will connect posts 30 and 87 which are wired inbetween the car battery +ve to the solenoid on the starter motor, correct?.

Am I going to require wiring a diode after the current comes out of the relay on pole 85, so that a higher current which is being switched on 30 and 87 does not try to escape or give feedback up back through pole 85?

Just edited my post, because it was not sounding correct to me..

Like this:

if its a bog std switched relay, wire it up as follows:
30 - battery + (or 13mm stud on starter)
85 - earth to battery or chassis
86 - starter red/black wire
87a - output to starter

HTH

rubjonny said

if its a bog std switched relay, wire it up as follows:
30 - battery + (or 13mm stud on starter)
85 - earth to battery or chassis
86 - starter red/black wire
87a - output to starter

HTH

Heya mate,

Thanks for putting me right on the relay!
Jesus I thought from reading the maplin Q&A would help me out but using their idea of wiring it up seems on it's side..

Now I've gotta get onto the wiring side of things. It's typical to have none of the wire you require and some of the stuff you dont.. All I've got sitting about is a load of 240v/13amp & some machine wire for my central locking which would only hold 6amp I should imagine. So I'd better get some XR58N High Current Wire (50/0.25) from maplin, but wondering if they have something a bit higher rated in the shop

Cheers rub, sound as ever matey
Kind regards,
Didge

I'd be tempted not to add a relay, its just another thing to have poor connections, go faulty, and have more wiring. Basically, its a bodge.

rubjonny said

 i have read that auto guys fit a relay on the solonoid wire to help with stuck starters due to heat soak, since the auto starter is on the back they suffer more from this problem.

I have heard that plenty of auto cars DON'T have an extra relay fitted, because they work absolutely fine. And also that some owners of manual cars add a relay becuase their starter motor solenoid is worn out.

Didge, is it definitely a worn out, or heat soaked, solenoid that's causing the issue here?

you may also need a relay for the same reason you add one to the headlights, due to poor voltage from the old wiring/ign switch.

would you call a relayed headlight loom a bodge and recommend people not to do it?

I already went thru all the steps you can go thru to test if a relay is actually needed, so hopefully the OP has gone thru all of that before rushing in to add a relay

Headlights and starter solenoids are different. The performance of headlamps varies with the voltage - the lower the voltage (due to various reasons for a voltage drop) the poorer the illumination. A starter solenoid doesn't have (shouldn't have) a varying performance, it has 2 states: engaged and not engaged. It should engage even at VERY low voltages, which occur due to (mostly) the resistance of the battery itself, during suppling the many hundreds of amps current to turn over and start an engine. If the starter circuit is poor, then there are additional voltage drops too.

Sure, a relay can apparently 'help' by buying a little more time before it eventually fails, but in essence a starter solenoid is not much more than a relay itself (it does engage the cog too, in addition).

Adding complexity and additional components, especially a relay for a relay, isn't the RIGHT solution for poor starting, its A solution but in my eyes its not the right one. The right thing to do is to make sure the starting circuit including solenoid is 100% working. Remember this is an auto, if it doesn't start, the car's not going anywhere, not like a manual where you can bump start it in an emergency.

paul_c said

I'd be tempted not to add a relay, its just another thing to have poor connections, go faulty, and have more wiring. Basically, its a bodge.

rubjonny said

 i have read that auto guys fit a relay on the solonoid wire to help with stuck starters due to heat soak, since the auto starter is on the back they suffer more from this problem.

I have heard that plenty of auto cars DON'T have an extra relay fitted, because they work absolutely fine. And also that some owners of manual cars add a relay becuase their starter motor solenoid is worn out.

Didge, is it definitely a worn out, or heat soaked, solenoid that's causing the issue here?

Heya Chris

Cheers matey, it's looking at the moment that I'm going to build the relay, install a heat shield and install a new starter motor this is all going to be done nearer the end of the month.

I also need to build a relay system for the headlamps so they use the full 12v.

Your both right, it has to be a tired starter and I'd do just about anything to have the car run when it's needed an without thinking all the time 'is it going to break-down in the middle of no-where, miles away from home!'

Now I know what your saying, if I install a heat-shield and a new starter I wont need the relay and that's also true so I'll re asses that when the starter is installed, but until then I think I'll use the relay add on

Cheers for your help lads, I would not have got this far if I did not have the experience you guys have offered and tbh I nearly booked the whole car in for a complete replacement of the engine bay wiring but that would have needed a trek out of town and miles away, that's even if the car got me there hehh it's also looking like we wont be able to attend the MK meeting as I don't know if I will get home well unless I get this relay in tomorrow or late this evening and test the car for a few hours

Your awesome fellas, thanks for all your help! Now I need to workout the wiring diagram for the headlamps I'd rather build it myself and make a thread so others can build their own like with this starter motor relay issue So I'll get onto that!

Kind regards,
Didge

Starter relay for heatsoak problems | VW Vortex - Volkswagen Forum

explains it perfectly, and even has a link to a proper VW bulletin explaining how to add a relay if the old starter trigger wire cannot supply sufficient voltage. so I maintain that installing a relay IS a good idea if you own an old automatic

Interesting thread there! Having had a good read of it, a number of people had a bunch of different starting problems, while some mentioned having the relay, others problems included:

- faulty shift interlock
- poor connection on the new relay
- worn out starter solenoid (relay didn't improve starting performance)
- new relay burning out or failing in other ways

And plenty of discussion on how to wire it up, and a few cases of missing heat shields.

yeah its a bit more of a pain diagnosing starter failure on these, personally I'd try to sort out the cause of the issue rather than go for the relay straight away, like you say its another layer of complexity.

if i did fit a relay it would be tucked up away from the engine somewhere relatively dry, and not under the header tank! trouble is on a mk1 the chassis legs are open underneath so more chance of having spary kicked up unlike a mk2.  a mate of mine put his headlight relays inside an old rubber glove then twisted shut to keep em dry

actually you could do the relay wiring behind the fusebox, as id imagine the run from there to the starter isnt that long on an automatic if its on the back of the engine? bit of a novice on auto mk1 wiring though