Wiring to fuse box

[Mike Robinson]

My HC has lost the supply to pins E2,E3,E4,E5 of the bulkhead connector, that is those terminals fed with the ignition ON through fuse 2. This seems to have happened after I used pin D5, which is also from ignition ON but un-fused, for an electric fuel pump supply (fed via a separate fuse).

There is still a circuit from the ignition switch to D5 but not to fuse 2.

I supose that there must be a broken connection between D5 and fuse 2, or possibly from some junction in wire 17 which provides the feed to from ignition ON to D5.

It looks as though it will need a lot of under-dash dismantling to access the plug and cabling there, so I would appreciate any thoughts or guidance on the problem

Thanks for your help


Mike

[1972nail]

I'll check the circuit diagram when I get time this evening. But I suspect it is corrosion of the terminals. You can lift the whole fuse box up a little and pull the wiring with it from under the bonnet, you won't gain much access but it might help.

You only really need to take out the small shelf on the driver's side and possibly the steering shroud to gain access.

[Mike Robinson]

Hi David,

I I have tried lifting the whole bulkhead connector out but as you suggest it doesn't give any useful access. The steering wheel and shroud are out but I guess I'll take the seat out in the morning (and put a pillow on the pedals!) so I can lie down on the job.

Mike

[fistfullofV5's]

Hi. This might not be relevant to your situation but when I was modding the electrics on my Firenza, I had an instance of one of the pins on the underside of the bulkhead multi connector coming adrift and cutting the circuit. It wasn't immediately obvious until I peered under the dash.
Regards,Dave.

[1972nail]

That's a thought, disconnect the battery and use a small screwdriver to push all the cables into the blocks, both below the dash and in the engine bay.

[droopsnoot]

If one of the individual wires has come adrift from the block, it's possible that the tag that holds them in place has stopped doing what it should, either because it's bent flat, or because it's broken off. Being able to remove the fuse box to gain access to the wires will make it much easier to fix that. I've found before now that trying to sort problems with the loom connectors for the inside of the car is much easier from above (by removing the screws that hold the fuse box to bulkhead and lifting it to then unclip the lower plugs) than from below. I guess it depends on how flexible you are. With the fuse box out of the way, you can see whether any connectors are pushed down and whether the tags are good, the latter would be very difficult from underneath.

[Mike Robinson]

Thanks for all the responses. I found there was an open circuit in the connector also that it can be split in half to get at the internal interconnections. Its quite interesting.

I found that a microscopic resistance weld had failed between pin D5 and the conecting strip to the fuse. I soldered it together and reassembled it and its fine.

I warmed the connector rubber mouldings before pulling them apart which seemed to make them more flexible and next time I will be sure to work over a clean bench as 19 pins are all ready to jump out when the connector comes apart!

Regards

Mike

[1972nail]

It's worth dipping the whole lot in some citric acid while it's out. That will take off all the corrosion. I posted a thread on here a while back.

[1972nail]

viewtopic.php?f=12&t=21726

Here it is.

[Mike Robinson]

Thanks for the reminder. I had read the tip about using citric acid elsewhere and dipped the connector a while back so it was still clean. I did run a thin scourer pad (the flat type) between the pins to take the tarnish off. I feel that in the end brass plugs and sockets rely on the sharp edge of the pin or socket to give a really low resistance contact.
Anyway it starts and runs fine now.

* I realise the last comment doesn't seem relevant but I was feeding the trigger circuit for the Accuspark from the previously open circuit pins as well as the auxilliaries