Replacing low-amperage cable to the starter motor / solenoid

[taylormj4]

Hi Folks,
Had an intermittent hot start for years but not frequently enough to be a nuisance. Replaced the complete alarm installation with a new META kit from Carl Baker as the original META system had started acting a bit weird (indicator staying on after disarming etc). Expected that this would resolve the hot start issue but it didn't and am now occassionally getting a cold start issue.

Have recently replaced the battery, so not that.

The low-amerage connector to the starter/solenoid has quite a poor spade connector on the end of it so suspecting that next. From experience, cutting off the connector will reveal corroded black copper cabling that it would be silly to crimp a new one onto. Also suspect the cross-section of this cable is too small or has become heat damaged so I want to replace it completely. I can see it runs up from the starter motor, into a black conduit and then over the back of the engine but not sure where it runs to then. Presumably to the immobiliser connector block.

Does anyone know the routing of this cable and whether it is possible to pull in a new one ? Also, where it terminates under the dash top?

Thanks.

[illmonkey]

No clue on the route (don't have a TVR - how did I get here?!)

But worth making a fly lead up to test it actually does something positive (excuse the pun...). Rather than going to all that effort.

[Belle427]

It will be found in that black loopback connector, a test lamp or multimeter will help find it obviously with the key in the crank position.
A common upgrade is to replace it and the larger starter feed from battery cable as they suffer with heat damage and were undersized originally.
As for the route it enters the cabin through the loom grommet in the bulkhead and is not easy to access, plenum removal is probably necessary to stand a chance.
Easier to pull a new one in really through some small protective conduit but its a bit of a pita getting it into the cabin due to the existing grommet being sealed up.
Some choose to fit a relay in the engine bay somewhere using the old solenoid cable to trigger it but that can be a little messy wiring wise, you can also add a relay under the dash for belt and braces should you go that way instead.

[taylormj4]

illmonkey said:

No clue on the route (don't have a TVR - how did I get here?!)

But worth making a fly lead up to test it actually does something positive (excuse the pun...). Rather than going to all that effort.

Haha great intro! Fair point and a sensible idea but I would like to replace the cable anyhow as suspect heat could have damaged the insulation in any case by now.

[taylormj4]

Belle427 said:

It will be found in that black loopback connector, a test lamp or multimeter will help find it obviously with the key in the crank position.
A common upgrade is to replace it and the larger starter feed from battery cable as they suffer with heat damage and were undersized originally.
As for the route it enters the cabin through the loom grommet in the bulkhead and is not easy to access, plenum removal is probably necessary to stand a chance.
Easier to pull a new one in really through some small protective conduit but its a bit of a pita getting it into the cabin due to the existing grommet being sealed up.
Some choose to fit a relay in the engine bay somewhere using the old solenoid cable to trigger it but that can be a little messy wiring wise, you can also add a relay under the dash for belt and braces should you go that way instead.

Thanks. Not had to remove the plenum yet. Is it a pain, e.g. does it need the fuel rail to be disconnected (not had to do that either) and if yes, how do you depressurise and repressurise it?

[sixor8]

The fuel rail is beneath the plenum, so doesn't need removing, but for information, fuel pressure dissipates slowly anyway. There should be a schroeder valve on the driver's side beneath the plenum edge that you can press to release residual pressure. The fuel pump will establish pressure the first time you urn on the ignition.

You'll need RTV sealant when refitting the plenum if you remove it. Air leaks will cause havoc with idle control.

[PabloGee]

I've done this job, you don't need to remove the plenum.

Whilst you're at it, there are a couple of other things you can do in the footwell to make it a better circuit.

Routing the cables to the starter motor is best done by disconnecting the big red cable from the bttery then the starter motor under the car, then tying a length of decent thin rope to it, and start pulling through from the footwell. Then when feeding the new (fatter) cables back through, you can spray a little WD40 on the grommet, and the new cables go through just fine.

Have a good read of this thread, and you'll get an understanding of what to do.

My journey started on page 7, I replaced and increased the gauge of:
the starter motor exciter cable
starter motor cable (to 50mm2)

I also fed through an earth cable - to run from battery negative directly to the engine block, ideally same gauge as starter motor cable, and fit to one of the mounting bolts of the starter motor.

I added a relay to the circuit for the exciter cable, to take the strain off the ignition key unit and immobiliser. Same principle as the 'hot start kit', but higher grade.

https://www.pistonheads.com/gassing/topic.asp?h=0&...

[taylormj4]

Thanks PabloGee,
Good info.

Are you talking about just the high-amp cable to the starter?
It is the small-gauge connection to the solenoid that I am interested in replacing as I think it is that that's causing me the problem. There is no click of teh solenoid actuating when I get the cold/hot start problem. The ignition lamps dim so I think the IGN switch is working and I haev replaced the alarm/immobiliser so think this cable is the only thing left.

Not keen on the hot start kit or relays in a similar fashion as it is just a patch on the problem. I want to pull out the low amp cable as I suspect it must be heat damaged and as my original post, the spade connector at the solenoid is just rubbish.

[taylormj4]

On further investigation yesterday, I can see the low-amp cable runs into a ribbed black duct that runs along the offside of the starter motor and then the duct stops but I can't see what happens / where the cables go after that.

Think I am only going to be able to see that if I remove the starter motor.
Does anyone know where it goes ?

[Belle427]

It runs along the back of the engine and into the bulkhead through a large grommet, its far easier to run in a new one through some protective conduit if you are going to do it in all honesty as the loom is tricky to get at without major part removal.
You could just replace the existing crimp on the end and save yourself some work, you can clean the copper wires first by using a solution of vinegar and salt mixed together and dipping them in it for a couple of minutes.
You do need to neutralise the acid afterwards with a solution of bicarb and water for a few minutes but this works very well with things available from your corner shop!

[PabloGee]

taylormj4 said:

Thanks PabloGee,
Good info.

Are you talking about just the high-amp cable to the starter?
It is the small-gauge connection to the solenoid that I am interested in replacing as I think it is that that's causing me the problem. There is no click of teh solenoid actuating when I get the cold/hot start problem. The ignition lamps dim so I think the IGN switch is working and I haev replaced the alarm/immobiliser so think this cable is the only thing left.

Not keen on the hot start kit or relays in a similar fashion as it is just a patch on the problem. I want to pull out the low amp cable as I suspect it must be heat damaged and as my original post, the spade connector at the solenoid is just rubbish.

That small amp cable follows that exact same route through the main loom grommet, and yes I replaced it with a thicker cable than the original - it's the solenoid exciter cable.
This was fitted to a relay in the footwell so the voltage coming through the ignition key barrel and immobiliser simply runs through the relay to earth, and the current into that exciter cable is direct from the battery positive via a 25A in-line fuse. The relay is a higher rated relay than the hot start kit.
I didn't remove the old wire because it was cut and disconnected for the old hot start kit in the footwell, and I just cut it back in the engine bay and put on a length of heat shrink insulation to cover the loose end and make it look intended for future reference.

Edited by PabloGee on Monday 2nd June 16:23

[THEDAVINATOR]

My next job(s) too - would it be worth hiring a ramp for a morning/afternoon to do this? There's a ramp hire place 1.5 miles away from my house...I found access to the starter with a trolley jack and axle stands pretty tight, and I hate crawling around under cars with next to no room...Also, the risk (minimised with axle stands I know) is a concern to me...."death by old car..." is something I could do without on the old death certificate

[PabloGee]

I did mine on two axle stands holding up the front, it wasn't roomy, but I'm skinny.

Doing it on a two or four post lift would be a lot easier, as you will have it up and down a couple of times to pull stuff through.
You will need to footle around in the depths of the footwell with battery and relay connections, then pulling chunky cables back through to the starter motor with a rope. But if you plan it a bit, you'll do it in concentrated stages:

e.g.
Car down
Disconnect big starter motor cable from battery
Car up
Disconnect big starter motor cable from starter motor
Tie strong but thin rope to starter motor cable eyelet, make sure there is plenty of excess, pull at least 5m of rope into footwell in case you need to go again with it
Car down
Unpeel carpet to reveal grommet through bulkhead
spray WD40 on grommet
Pull big starter motor cable and therefore rope into footwell

Buy or build 50mm2 red starter motor cable - approx 2.1m, but measure what comes out (I ended up buying all the parts and crimping tool to make it up because I wasn't sure of the length needed, and didn't want to wait)
Buy or build 50mm2 black earth cable - approx 2.1m
Length of 3mm2 black cable for starter motor solenoid exciter - approx 2.1m
tie/strong tape them to the rope
spray more WD40 on the grommet

Car up
pull it all through in one go (because you may only get one chance with the rope)
Connect it all up, including the relay on the exciter cable.

Car down
cut the old exciter cable back and tidy up - you can't remove it because it's wrapped into the main loom

[Belle427]

Get some ramps from machine mart, in a push i jack cars on to them if driving up them is a bit sketchy, you can buy the extenders too for low cars.
You do need a good large trolley jack though, can be a bit of a pita getting it up high enough but its a lot safer.

[PabloGee]

Agreed. Getting a system for home is helpful, more accessible and cost effective.

[taylormj4]

Belle427 said:

It runs along the back of the engine and into the bulkhead through a large grommet, its far easier to run in a new one through some protective conduit if you are going to do it in all honesty as the loom is tricky to get at without major part removal.
You could just replace the existing crimp on the end and save yourself some work, you can clean the copper wires first by using a solution of vinegar and salt mixed together and dipping them in it for a couple of minutes.
You do need to neutralise the acid afterwards with a solution of bicarb and water for a few minutes but this works very well with things available from your corner shop!

This was my preference but very limited wire slack. If I cut off the existing crimp don't think I will get a crimp tool back in there and if I did manage to, there's probably not enough slack for it to reattach to the solenoid.

Interesting vinegar/salt solution thing. Not heard of that one. Great if it works. Replaced a lot of wiring on an old Range Rover and ended up cutting back 10s of cm into some of the wiring before it got less black, then had to use sandpaper to clean up the copper wire enough for solder to stick to it.

[taylormj4]

PabloGee said:

That small amp cable follows that exact same route through the main loom grommet, and yes I replaced it with a thicker cable than the original - it's the solenoid exciter cable.
This was fitted to a relay in the footwell so the voltage coming through the ignition key barrel and immobiliser simply runs through the relay to earth, and the current into that exciter cable is direct from the battery positive via a 25A in-line fuse. The relay is a higher rated relay than the hot start kit.
I didn't remove the old wire because it was cut and disconnected for the old hot start kit in the footwell, and I just cut it back in the engine bay and put on a length of heat shrink insulation to cover the loose end and make it look intended for future reference.

Edited by PabloGee on Monday 2nd June 16:23

Is this main loom grommet in the passenger footwell under the dash top?
I dont have the hot start kit fitted so was expecting the solenoid exciter wire to run to the plug by the immobiliser under the dash top. Is that the orgininal route if you dont have the hot start kit? Or does the exciter wire run to the relays in the footwell?

[taylormj4]

Belle427 said:

Get some ramps from machine mart, in a push i jack cars on to them if driving up them is a bit sketchy, you can buy the extenders too for low cars.
You do need a good large trolley jack though, can be a bit of a pita getting it up high enough but its a lot safer.

I have drive-up ramps but I find the TVR nose hits them so you need to use wood blocks in front and then the TVR tends to push the ramps away instead of climbing up them. Bought those plastic ramps that taper to next to nothing and those are much better but only lift the car a couple of inches but enough to get a trolley jack under and jack onto stands. Using the two ramp types together works well (I tie them together to stop them separating).
Have you tried the mini hydraulic lifts that you put under each wheel?

[Belle427]

Not tried them.
I did buy a pair of the ramps that you wind up and down manually from Facebook which were a steal.
Not confident working under them without axle stands though but they are a great idea.

[PabloGee]

taylormj4 said:

Is this main loom grommet in the passenger footwell under the dash top?
I dont have the hot start kit fitted so was expecting the solenoid exciter wire to run to the plug by the immobiliser under the dash top. Is that the orgininal route if you dont have the hot start kit? Or does the exciter wire run to the relays in the footwell?

Yes it's the main grommet in the passenger footwell, not 'under' the dash top, rather below the dashboard structure.
Apologies I don't have a photo and I've glued my carpets back down.

The solenoid exciter wire comes into the footwell to a black plastic loopback connector in the footwell, it sits in the nest - which is what is cut for the hot start kit.