R500D start/stop button and instrument PCB

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bluenose
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R500D start/stop button and instrument PCB

My recently purchased R500D has an intermittent issue that when I try turning the engine off the car remains running. I have replaced the Savage switch and contractor block with a new one which I thought was defective as the block was not fitting snuggly on the switch body but the car is still the same.  Anyone else with a R400/500D had this problem? I am starting to suspect the instrumentation PCB, see link below.  Seems to do it when the car is warmed up and the only way to shut the car down is the stall it and disconnect the battery.

https://caterhamparts.co.uk/other/3751-instrumentation-circuit-board-r500-seven-485.html

Jonathan Kay
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What's the history of the car? And any recent work on it?

Does it have a battery cut-off switch?

Is the alternator behaving normally... measure battery voltage at rest, minimum during cranking, and at 3,000 rpm. Does the warning light behave normally?

If you disconnect the fan(s) when it happens does the engine stop?

Jonathan

 

bluenose
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Hi Jonathan.  Car is 12 years old with <3000 miles when I picked it up so not much use in that time.  No battery cut off switch, going to get one fitted soon.  Has a new Banner battery, charging I would say is normal(why wouldn't it be, not sure of the relevance, it starts and goes ok).  No voltage problems indicating on the dash.  What is the reasoning behind disconnecting the fan, it does not cut in until about 100 degrees anyway and car is not that hot when I go to switch it off?

Nick

ScottR400D
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I could be wrong but I don't think the PCB would control that. I thought it was more to do with lights, indicators, wipers etc.

Having said that they're not the most robust of boards. I had two fail within a year of my car being new in 2015, both indicator issues. The third one has continued to function since 2016, though I bought a spare board at the time, for two reasons.

Firstly because I'm not convinced of the quality and secondly because I wonder how long CC will keep them available. I think it's only used on the 485R, if that, At just over £200 it's not a bad spare to have IMO.  

 

L7C
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When I had mine off I changed the way it's mounted. Normally the board is simply screwed up against the bulkhead with 4 screws coming in from the engine compartment. I put anti vibration mounts on those screws so the board is now fixed to the AVMs with nuts. 

So no need any more to move the heater to change the board and it's protected to some extent from vibration. 

If you change the board I'd recommend that you do that too. 

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bluenose
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Thanks Scott. I suspect it does come through the board as the board has relays to control the higher current the switches cannot cope with. The tip regarding AV mounts sounds sensible. Do you have any photos of you fitting it?

N

ScottR400D
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I think I do. I'll dig out and post. Yes, you could be right about the relays. 

Re the AVMs its pretty straightforward. Unplug the 3 (IIRC) connectors from the board and then unscrew and move the heater out of the way and unscrew the 4 screws that hold the board in place. Again from memory there were rivnuts in the holes of the board but the new one didn't come with them. If they're there they need to be removed.

Fasten the 4 M/F AVMs in with the original screws, I put a penny washer under them as you can see, position the board and put a nut and washer on each to retain the board.

Now its just a few minutes work to change the board. Not that I've had to since doing this!

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bluenose
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Appreciated Scott.  My car was purchased from Millwood and Jon has been excellent at sorting out some issues with the car. It will be looked at by them/ their chosen repairer but I am a little worried about the intermittent nature of the fault and the distance to the repairer so trying to work out if it has been an issue with other cars.  From your post it sounds like the board can fail.  Agree that it seems like a good idea to have a spare board.

Nick

rj
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How are the cables from the switches routed and secured?

 

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bluenose
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Good question, almost impossible to say without removing the scuttle. In fact I cannot even locate the main board, it's not above the heater like Scott's car? From what I can see the car wiring is not the neatest.