Area Representative bluenose Posted October 10, 2021 Area Representative Share Posted October 10, 2021 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 Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted October 10, 2021 Member Share Posted October 10, 2021 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 Link to comment Share on other sites More sharing options...
Area Representative bluenose Posted October 10, 2021 Author Area Representative Share Posted October 10, 2021 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 Link to comment Share on other sites More sharing options...
ScottR400D Posted October 10, 2021 Share Posted October 10, 2021 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. Link to comment Share on other sites More sharing options...
ScottR400D Posted October 10, 2021 Share Posted October 10, 2021 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. Link to comment Share on other sites More sharing options...
Area Representative bluenose Posted October 10, 2021 Author Area Representative Share Posted October 10, 2021 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 Link to comment Share on other sites More sharing options...
ScottR400D Posted October 10, 2021 Share Posted October 10, 2021 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! Link to comment Share on other sites More sharing options...
ScottR400D Posted October 10, 2021 Share Posted October 10, 2021 Link to comment Share on other sites More sharing options...
Area Representative bluenose Posted October 10, 2021 Author Area Representative Share Posted October 10, 2021 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 Link to comment Share on other sites More sharing options...
rj Posted October 11, 2021 Share Posted October 11, 2021 How are the cables from the switches routed and secured? Link to comment Share on other sites More sharing options...
Area Representative bluenose Posted October 11, 2021 Author Area Representative Share Posted October 11, 2021 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. Link to comment Share on other sites More sharing options...
ScottR400D Posted October 11, 2021 Share Posted October 11, 2021 Ahh, it's not there? That surprises me. It is quite a big thing (250mm x 100mm x 35mm) so shouldn't be hard to find if it's there. Link to comment Share on other sites More sharing options...
Area Representative bluenose Posted October 13, 2021 Author Area Representative Share Posted October 13, 2021 Scott, finally had chance to look for the main board tonight. Being an R500 there is spare room behind the dash on the passenger side. It is situated here. All the plugs look well seated and the board looks fine. I would love to know who made it for Caterham and what the 9 pin D type plug is for, assume some sort of test rig connection? Nick Link to comment Share on other sites More sharing options...
rj Posted October 14, 2021 Share Posted October 14, 2021 The D-Sub connector will likely be for flashing the processor. Do you hear a realy klicking when the car won't start? It could be one of those that has started to fail. Unfortunately it looks like it's all glued in some sort of epoxy and therefor extremely difficult to repair. Link to comment Share on other sites More sharing options...
ScottR400D Posted October 14, 2021 Share Posted October 14, 2021 The boards are heavily filled with potting compound, it's hard to see how you'd dig out any particular component, even if you knew which was faulty. Link to comment Share on other sites More sharing options...
Hampshire West AR Posted October 14, 2021 Share Posted October 14, 2021 RJCar will always start but will not always stop. If I stall the engine the dash sits there lit up and making a buzzing sound but the start/stop button fails to turn off the ignition. The immobiliser seems to be working fine and as expected. All other switches seem to function ok when driving. If I disconnect the battery and reconnect then the ignition remains off and I can restart the car, but then have problems switching off again. At the weekend I drove to Compton Abbas for breakfast. Car would not turn off there so disconnected battery and reconnected, this was after fitting the new start switch. Drove home and same thing. I am wondering if the problem is related to the lights being on or heat as I have popped to get fuel without the lights on and it has worked fine.Nick Link to comment Share on other sites More sharing options...
rj Posted October 14, 2021 Share Posted October 14, 2021 That could be a relay that has started welding the contacts. You could tap the top of the relays when it won't stop and see if anything happens. Tap IE with the handle of a screwdriver. Link to comment Share on other sites More sharing options...
Area Representative bluenose Posted October 14, 2021 Author Area Representative Share Posted October 14, 2021 There are 14 relays on the board, gonna be lucky to find which one is sticking. Link to comment Share on other sites More sharing options...
rj Posted October 14, 2021 Share Posted October 14, 2021 But still it would indicate that it's the relay unit that's faulty, and as you presumably can't replace a single relay due to the resin, then you just want to know there is a fault ;-) Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now