No power getting to the starter motor!

[Bucky P]

I've lost power getting from the ignition switch to the starter motor on a 1.6TD. We had a problem a few years back where there wasn't enough power getting to the starter to run it so I fitted the aux relay in the engine bay using the ignition cable to the starter to energise the relay and a line directly from the battery through the relay to the starter, this has worked fine for years. Tried to start up the other day and nothing happened, the glow plug relay appears to be energising but nothing is getting from the ignition switch to the aux relay to run the starter. Looking at the wiring diagram, there is a cable junction where the feed to the glow plug relay branches off from, does anyone know where this junction is located?
From what I understand, the cable from the ignition to the starter motor can break down over time reducing it's current carrying capacity, thus, the need for the aux relay where there is enough power to energise the relay but not run the stater motor? I think I'm going to have to rewire from the ignition to the glowplugs and starter motor to resolve this and do away with the aux relay?
Any advise greatly appreciated.

[Robsey]

My first port of call is always the ignition switch.

Have you got battery voltage at the 50 terminal when cranking.
If not, chances are your switch contacts have become pitted and no longer effective.

A new switch is quite cheap.

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If you think it is engine bay related, then you may have a connection in or close by to the junction box.
At best you may have a loose connection, or a worst, the wire is dirty or damaged.
Red and black wire is your cranking wire.

The only way to know for sure is a visual check, and checking for voltage at each joint.

Finally - is it possible that your relay is at fault.?
There are a lot of relays knocking about on places like ebay etc; of unknown quality.
A lot of mixed quality China-import stuff flooding the market.

[Bucky P]

It's definately not the ignition switch, I took the connector plug off the back and shorted the link out to check the line from the ignition to the aux relay at the back and nothing was getting though so it is a broken or corroded cable/ joint. My problem is trying to find where the cable runs are and where the cable joints are so I can check continuity or replace the cabling. The cranking wire goes straight to the starter/ aux relay from the ignition through one joint from what I gather, and I expect the issue is at the joint but I don't know where it is located and havent been able to find it as yet. 

[RogerT]

I don’t think there is a connector. Wiring diagram available from syncrosport website shows a 4mm ro/sw (rot/Schwartz in German, red black in English) going from 50 pin on ignition switch to B8 on fuse board, which connects internally to D24, from where a 6mm ro/sw goes to pin 50 on the starter solenoid.

You’ll have an aux relay somewhere on there.

This wire, robsey called it the cranking wire, I know it as the trigger wire, often corrodes badly for a foot or more from the solenoid, due to its exposed location. Replacing the wire solved my starting woes.

[Mocki]

Aux relay ?? Do you mean the x relief relay in the fuse box or is there a bodge “hot start” relay between the ignition switch and the starter solenoid ?

[RogerT]

I’m guessing the op means a hot start relay, judging by their description in the starting post. Superfluous if your wiring is up to scratch…