Sigma instruments all dead

[K7 VCT]

On the fish and chips run today, along the heads of the valley road, the speedo , then a others failed, the fuel gauge was last.

No indicators either, but lights and hazards are working.

Checked battery terminals and earth I could locate all tight.

Fuses all looked ok to.

Didn't fancy a mid Wales breakdown so decided to head back to Oxfordshire.

All ok ,except all electrical items above still dead, have switched off and on a few times with battery isolation.

I need a wiring diagram for a sigma. ti- vct car of 2014, so just before the new dials etc that came in late 2014.

Any ideas of common issues? If anyone else has had this.

[Jonathan Kay]

Please send me a Private Message with your email address and I'll send the wiring diagrams.

Jonathan

[Jonathan Kay]

1 Is this a dash with separate gauges rather than eg a Stack?

2 Which indicator warning system... one or two lights, and where are they?

3 Any recent work on the car?

4 Have you found and checked the instrument earth point?

5 Do you have a multimeter?

Jonathan

[K7 VCT]

Hi Jonathan, thank you.

 

No recent car work.

 

Yes I've got a multi meter in my tool bag

 

Standard caterham instruments, speedo, rev counter,

Fuel, oil pressure, temperature.

 

The car rev counter has 2 green led tell tales for indicators, one for left, one for right, also a high beam blue led.

Speedo is electric, trip counter, mileage are electrical too.

 

Not looked for any earths other than battery to chassis under bonnet.

At the roadside , i think there may be one by the fuses and wiper motor, but not sure as yet

 

Cheers julian

[K7 VCT]

Your message box is full

Jonathan

[Jonathan Kay]

Sorry: diagrams sent.

1 There are at least 3 different layouts of fuses and relays on Sigmas. I’d check carefully what you’ve got.

 

2 Working hazard lights with failed indicators means that you should check the flasher unit/ “relay”. It also sometimes happens with a common fault in the hazard warning light switch: cycle that a few times and see if it makes any distance.

 

Jonathan

[K7 VCT]

Cheers Jonathan, not sure the common hazards issue would stop all gauges working. But will try anything.

 

Julian

[SM25T]

Over long cable to speedo sensor on rear wheel. Cable tied to A-frame or chassis during assembly. Chafed through at a cable tie. Stopped a lot of electrics ...happened on a friends car on a tour.

[K7 VCT]

Thanks SM25T, someone maybe you said about it on facecloth, would have thought a factory built car would be ok, will check it this afternoon if I get time.

[ScottR400D]

Harnesses are fitted at the factory on kits so no difference. 

[BigCol]

K7 VCT said "...would have thought a factory built car would be ok..."

you're new to Caterhams aren't you...?  

[SM25T]

Hahaha

[K7 VCT]

Bigcol, err not quite, 3rd car 12 years of 7 ownership ..

May be a hint of sarcasm in my posts...

[Dave Hardcastle]

With so much failing at the same time, I'd be inclined to look around the main fuse board. Connections to and from, the fuses themselves etc.

[K7 VCT]

Thanks all, will get round to it in the week, will post findings.

[ChrisC]

Finding a wiring diagram is going to be difficult.  The last wiring diagram published (I have seen) was in the 2015 build manuals, unfortunately this Sigma diagram show components that weren't on my 2011 Sigma car, and hadn't been for some time, i.e. a MFU unit. Also there were wires missing from the engine to chassis loom connectors.

From what I remember the Tacho has a voltage regulator in it, which powers most of the gauges.  If that happened to me I would be inclined to look at the speed sensor, but you said no fuses had blow, which is the strange part.   The speed sensor (or should I say the suspension would have been getting a good workout hence my suspicion.  The speed sensor tends to blow the instrument fuse, which (on Duratec cars anyway) also kills the ECU.  Much like a short in the indicators car kill a Duratec ECU.  Hence I always run LED fuses. 

Use the pin out diagrams on the smiths instruments support pages to see if your tacho is providing the voltage for the other instruments. 

[ChrisC]

Just looking at the out of date diagrams, the instruments fuse will kill all the gauges, and the ignition relay.  If you kill that relay its a non starter.  The green wire to the gauges should be you feed.  Beyond that check the earth on either side of the chassis.

[K7 VCT]

Thanks chris c, Jonathan has sent me some wiring diagrams, hopefully ones is for my car.

Mines one of the last ti- VCT sigma before the new AP front standard brakes and new instruments and lack of brake fluid test switch on the dash.