Sigma Alarm
 

Does anyone know which 2 circuits the standard UK Sigma Alarm switches, I believe one is the supply to the fuel pump relay, can someone confirm the second is the feed to the starter motor?

Next question is, where is the box located and can you get into it? Need to do some investigating after I was briefly left stranded at the petrol pumps earlier when it wouldn't start.

Shane

Search for a chap called Sigma Sam, I did have his number, but that was years ago.

Helped me out once I confirmed with him I wasnt a pond life trying to nick the car :-D

Could be cam or crank sensor as these can give hot start issues.

Wouldn't turn over at all, the same as when the immobiliser cuts in 30 seconds after disarming the alarm if you don't turn the ignition on.
Sigma Sam cropped up in a search I did yesterday.

I've heard of the relay contacts getting dirty in the alarm module so was going to take a look. It fired up 20 minutes later while I was on the phone to the RAC.

Ah my V1 used to do this, I swapped out the fuel pump relay and it hasnt done it since. Its tucked right up under the dash so its a pain to do.

Just done the fuel pump relay as the pump was failing to prime when I turned the ignition on and so fixed that problem. Saturday it all lit up, immobiliser light went out but turning the key did nothing, no click, no dimming of dash lights.

Was it a station you use regularly? Could it have been the old 'unshielded' problem that effects the sigma's....... maybe some aerial nearby causing problems? Mine used to have problems at beachy head, but keep trying and it would go sometimes...

Wasn't that Ron as I could arm and disarm the alarm with the remote, my theory is that the relay in the control unit that switches the starter feed didn't switch properly, when I had problems the other day it would turn over but there was no supply to the fuel pump, this time the fuel pump would prime but it wouldn't turn over. I think it would probably have bump started but didn't want to be stuck at the bottom of the hill on a main road if it hadn't started.

This problem has reared its head a couple of times recently so decided to investigate further, managed to locate what I believe is the control box with the intention of changing the relays out for new ones

https://farm2.staticflickr.com/1727/...011e010d_c.jpg

Now the biggest problem is that it is held in with either a T6 or T8 Tamper proof torx and Nyloc nut, obviously I only have down to TP10 so a set of bits are on their way courtesy of Amazon Prime.

https://farm2.staticflickr.com/1754/...8702ec83_c.jpg

It's well packed in, I can't even access the loom.

https://farm2.staticflickr.com/1724/...a3cb8af9_c.jpg

While poking around tracking wires this earth wire turned out to be loose, the blue crimp tells me it wasn't fitted at the factory so I've tightened it up and keeping my fingers crossed it may be the source of my problem, tempted to swap out the relays anyway, the contacts could be well furred up after 19 years.

https://farm2.staticflickr.com/1743/...ec0b4660_c.jpg

Fingers crossed.
You managed to crawl back out from the footwell then.

Wish I'd taken the lower dash panel out to change the fuel pump relay, nearly crippled myself doing that and you can see it easily with the dash removed.

Halfords sell a torx set or b&q sell the mac tool torx set aswell .

Always have tools like that about if you ever need to borrow any.

I had everything but the size I needed, set turned up today, you can never have too many tools anyway.

Found it

https://farm2.staticflickr.com/1784/...2e62c08e_c.jpg

That has got a little warm

https://farm2.staticflickr.com/1753/...784d511a_c.jpg

And that won't be helping matters

https://farm2.staticflickr.com/1789/...b98962ab31.jpg

I've re-flowed all the suspect joints, could well have been caused by the bad earth. Only time will tell now, I'll put it all back together and see what happens.

Bugger, turns out I haven't fixed it, finger is now pointing at starter motor as I gave it a whack with a wheel brace on the Shell forecourt and it started. Only ever does it when hot and has been switched off for a few minutes.

My RS Turbo used to do the same. Had to push it off a forecourt more than once. Heatsoak stops the starter throwing into the flywheel.

Hope that sorts your problem. Out of interest can you pm me where the Signs unit is in case I get trouble ?
👍

My supra had the same thing. Once hot the starter was dead. Apparently a very comman issue on the TT mk4 so new one was fitted and never did it again.