Roadsport K Series Intermittent Electrical Fault.

[Videocameraman]

My 2006 K series has a very occasional electrical glitch. Occasionally on turning the key the ignition light comes on but engine does not turn over to start (pressing the starter button!). There is a very quiet buzzing / clicking sound and the rev counter and speedo needles vibrate anti-clockwise. nothing else. Could the sound be some relay not operating correctly? After a number of attempts it seems to work again. There has been over 2 weeks between these occurrences. very intermittent. Any suggestions welcomed.

[Jonathan Kay]

Have you got a multimeter and would you like the wiring diagrams?

Jonathan

[Jonathan Kay]

I'd start by investigating whether there's an intermittently bad connection in the ignition switch.

Jonathan

[Videocameraman]

I have a very basic multimeter. Not sure how to proceed from here. My knowledge is as basic as the multimeter. How can I check for bad switch connection? The red ignition light comes on every time.

[Jonathan Kay]

You can check that switch by measuring the voltage between any ignition-switched circuit (such as the feed to the starter switch) and earth as you fiddle with the key in the switch. 

But if you're already sure that the ignition light doesn't go out or flicker when the problem occurs then that is against that being the problem.

...

There's a lot of different causes of bad starting and clicking in the archives. Including the relay in the MFRU.

https://duckduckgo.com/?q=site:caterhamlotus7.club+click+k

I suggest trying to narrow this down by using the voltage range on the meter and measuring the voltage across the battery:
• At rest
• Minimum during cranking
• At 3,000 rpm,

I'd also check all of the relevant wires and connections: battery, starter, engine earths. 

Jonathan

[Wrightpayne]

I've two points worthy of mention

Firstly, I've had an ignition switch fail and the car wouldn't start. When turning it the red charging warning light didn't come on ie no power to any ignition switched circuits. This should be easy to test for, with a multimeter and wiring diagram. I fitted a replacement land rover switch (from Rimmer Bros) into the existing lock barrel thus keeping the original key.

 

Secondly, the K series 'click' is a known fault where one of the relays within the Multi Functional Relay Unit (MFRU) fails. Googling these terms should yield some solutions.

Reading your description I'd start with the second suggestion.

Ian

[SLR No.77]

Has this car had the "K-Series click modification"?

[tangomikeromeo]

Another unhelpfully vague shout from the crowd is 'dodgy earth!'

Is there corrosion/paint/oil/anything on the earth connection? Both ends at battery and chassis?

[Videocameraman]

Not unhelpful at all. The garage who checked the battery suggested the same thing!

[Dave Hardcastle]

My last Caterham was a 1.6 K-Series. Every so often, intermittent, I'd get the dreaded click on turning the ignition.

Put the car in gear, handbrake off, then roll it back and forth, jerking the drive train. That always allowed me to then start the car normally.

If that gets it started, it would be worth cleaning all the battery lead connections, including at the kill switch if you have one.

Hope that's of help