Mystery wire...?

[spanishfly]

Finally finished rebuilding the 2.1 engine in my syncro learned a lot along the way. I started it today and am working through a few electrical teething issues. 
The engine does seem to run really well but am puzzled by the following:

There appear to be 2 cables that aren't connected. 
Both have 2 wires and rectangular connectors with rubber boots like sender wires? 

1 is very close to the syncro tank sender and is short.

The other is very long, long enough to reach anywhere in the engine bay brown and blue/brown....?


The other gremlin is that the indicator light is permanently on and if the headlights are switched on the rev counter stops working and the water temp light starts blinking..... The dash is hardwired with Chris's kit and prior to the rebuild didn't do anything strange. I did look at his pin out but can't see the connection between the rev counter , indicator and the flashing light??? Any ideas would as ever be much appreciated  
 

[Syncronorth]

Nr 1 might be going reverse light or rear diff locker? 
​​
Have you connected the wire that goes on top of the coolant expansion tank? 

​​​​​​

[Mocki]

The headlight, red flashing light thing is almost definitely a earthing issue , most likely in the engine bay . 

[spanishfly]

Thanks rear diff locker sounds promising. I'd not managed to use the van prior to rebuilding the engine and don't remember seeing or more importantly reconnecting anything to the rear diff. I'll have a ferret! Yes! that will be it, thanks! It's long so it can reach over the gearbox not into the engine bay now I remember. 

[spanishfly]

I thought earth too, all the earths I could find and wiring to temp senders x2 , dops x2, reversing light, AFM, heater, cigar tube, TPS, Hall, ICU, coil have been cleaned and  reconnected which brings me back to the very long wire? Is there supposed to be a main earth between syncro gearbox and chassis or starter motor and chassis? I'll get my multimeter out.....!
Cheers Simon

[Aidan]

there should be an braided earth from below coil to engine block and a braided earth from chassis mount for gearbox to front of gearbox case, but you can make a connection from chassis to lower starter motor stud which will provide better earth routing for the starter
it's just possible that one of the 2 pin plugs is for a decoupler, usually cable tied to the wiring loom as not fitted in production, otherwise the other short one is likely the reverse switch connection

[spanishfly]

Thanks Aidan good call!
The shorter one does have green corrosion inside, as such may well be have been clamped in between the tank and chassis rail unused. 

[spanishfly]

Just to wrap this one up. Thanks for the wisdom everyone. 

I assumed engine bay as I'd had the engine in and out.... twice! But turned out that the PO had fitted or maybe there always was a tell tale light for the tow bar electrics in the lower heater panel that took a feed from the flasher relay. The earth to which wasn't earthing. I redirected it to the cleaned in vinegar crown behind the fuse box and everything now works as it should. haven't tested the tow bar but that can wait.

Still searching for the non earthing brown/black from the diff actuator panel??
 

[Aidan]

brown black is the decoupler, afaik all the Syncros have it in the loom even though it wasn't fitted in the factory, same as front difflock plug is there even if not fitted and rear is there if not fitted, all because the violet/black for fuel sender is required on all vehicles and was added into the difflock loom on Syncros, so non difflock vans have the loom with the violet/black heading off into fusebox to connect to the dash loom and a 3 pin plug hanging above the fusebox doing nothing and two earths in the engine bay with 4 brown connections, wasteful but good for us as saves having to run extra wiring when adding functionality to the vehicle for these functions

the plug cover fitted to the decoupler plug does seem to vary though, sometimes it is the round 191 one, sometimes the smaller 024 one as per the level switch, I don't know if this is a year or market thing

[Aidan]

wiring diagram for difflock

AndySyncrosportreallyusefulstuff