Benton Posted August 25, 2021 Share Posted August 25, 2021 Time to get this thread going again with another "opportunity" ..... So last month I noticed occasionally the immobiliser light would start flashing whilst I was driving along!, flashing lasting for about a minute and then stopping. Car in the meantime ran perfectly fine. Used the car yesterday, ignition on and off / started at least a couple of times perfectly fine.This morning at home disconnected the conditioner, tried to start the car, immobiliser wouldn't disarm, kept the rapidly flashing state till it got bored and rearmed itself.Tried disconnecting/reconnecting vehicle battery, playing with inertia switch, spare key, messing with the "aerial" pickup wire etc. - nothing. No real reason to suspect vehicle battery (though it is 3 years old), reads over 13v when turning the ignition key to the "on" position (though of course it's not actually doing much at the time, no fuel pump, no engine cranking), besides battery had no problem cranking the engine over yesterday. The immobiliser is the standard Sterling (passive key) setup. Anything else obvious to check whilst waiting (not so patiently) for the Caterham truck? Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted August 25, 2021 Member Share Posted August 25, 2021 I don't see anything in the Sterling User Guide or the Handbook that will help.But I would suggest checking the battery condition when possible, as outlined upthread. Some Sevens will still crank the engine when the voltage has dropped too low for the electronics.Jonathan Link to comment Share on other sites More sharing options...
Benton Posted August 25, 2021 Share Posted August 25, 2021 Thanks Jonathan, I'll try tomorrow with some jump leads/another battery and see what happens. Of course if I can't get the fuel pump on/engine to crank in the first place then I haven't got a lot to measure Link to comment Share on other sites More sharing options...
Benton Posted August 26, 2021 Share Posted August 26, 2021 So just hooked the Caterham up to my daily's battery same result won't disarm.Now where's that whiskey........ Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted August 26, 2021 Member Share Posted August 26, 2021 !On fuel pumps... what model of Seven is it? Jonathan Link to comment Share on other sites More sharing options...
Benton Posted August 26, 2021 Share Posted August 26, 2021 620R Jonathan.Just for fun just checked the fuses (immobiliser and fuel pump) both ok, made a strange, hopefully totally unrelated, discovery in that according to Caterhams diagram/spec the fuse for the instruments should be 7.5A but mines got a 30A one fitted instead! Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted August 26, 2021 Member Share Posted August 26, 2021 Thanks. I don't know how the immobiliser relates to the fuel pump on those. So I won't refer to: "K Series Immobiliser & Fuel Pump - Setting The Record Straight"; -(Jonathan Link to comment Share on other sites More sharing options...
Benton Posted August 26, 2021 Share Posted August 26, 2021 Thanks Jonathan.In "normal" operation the immobiliser light goes out and the fuel pump primes it seems almost simultaneously. The fuel pump/sender unit has been in and out the car a couple of times by Caterham, so could possibly be a culprit. Whether a problem with the fuel pump side of things can affect the immobiliser disarming then I'm I don't know. I've checked the fuel pump loom as far as I want to go, a known problem is that the rear exhaust hanger can "chop" its way through the loom, thankfully there's plenty of distance between the two. Whoever last put the fuel pump back got a bit carried away with cable ties, plus the fuel pump module is screwed to the boot floor, so further investigating the connections to the fuel pump involves effort which I don't think is worthwhile, besides which the car is under warranty and so I don't want to "fiddle" to much.The only other area I haven't checked is to see if the immobiliser "aerial" wire actually plugs into the immobilser (and has come loose for some reason) or is it hard wired. There's only a couple of illustrations/parts listed on the Caterham website which include the immobiliser and main loom together so it's hard to tell. Further investigation will also involve a battle with the cable ties Link to comment Share on other sites More sharing options...
aerobod - near CYYC Posted August 26, 2021 Share Posted August 26, 2021 in that according to Caterhams diagram/spec the fuse for the instruments should be 7.5A but mines got a 30A one fitted instead! Be careful to verify that the fuse diagram is correct, on my R400D the fuse order is correct to the diagram, but they are ordered bottom to top instead of top to bottom. Not sure if it is due to the fuse block being upside down or the diagram being incorrect. Link to comment Share on other sites More sharing options...
Benton Posted August 26, 2021 Share Posted August 26, 2021 Out of curiosity pulled it out .... no instrument (tachometer / speedometer) sweep plus the other fuses correspond OK to the diagram Link to comment Share on other sites More sharing options...
ChrisC Posted August 26, 2021 Share Posted August 26, 2021 Gong to say, I don't trust the fuse layout in the owners manual. Just checked the 620 chassis loom diagram, showed fuse F, Instruments D.C.M, 20A. Link to comment Share on other sites More sharing options...
Benton Posted August 26, 2021 Share Posted August 26, 2021 So if anyone is remotely interested .... the immobiliser aerial does indeed have its own connector, which of course was perfectly sound. Beyond that connector are two (apparently) identical black wires that seem to disappear into the general electrical spaghetti abyss near the top of the scuttle, heading in the direction of the "fuse box", where I'm guessing the actual immobiliser is lurking somewhere nearby. Tomorrow's task for curiosity is to hunt down the immobiliser, you'd assume it has its own connector, .as well as checking the soundness of the overall connection to the ecu. Joy .... Link to comment Share on other sites More sharing options...
ChrisC Posted August 27, 2021 Share Posted August 27, 2021 Have you checked Fuse R, "Keyless Immobiliser" 5A ? Link to comment Share on other sites More sharing options...
Benton Posted August 27, 2021 Share Posted August 27, 2021 Yep, fuse checked OK, supply voltage to fuses Ok, immobiliser found but no obvious visible connector found (at least without having to disturb too many other cable ties/loom parts etc.), disconnected/reconnected ecu connection. Still no joy. Ran out of ideas so I've thrown in the towel . Managed to persuade the RAC to get the car transported to Gatwick. If it turns out to be it's something simple I'll kick myself!, we'll see. Link to comment Share on other sites More sharing options...
Area Representative Geoff Brown Posted August 28, 2021 Area Representative Share Posted August 28, 2021 Over the years I have had related problems with my Sterling Excel remote security system - no key just the little solid state tear drop shaped fob that talks to the transceiver cable loop under the centre 'storage' area.In the end it was all down to the Banner battery either on the way out or just expiring. The red LED would flash or not extinguish, no pump noise, the gauge needles would go FSD or stop at half way & refuse to budge.After a cranking check a new battery sorted the problem out.As has been postulated by myself & mentioned above by JK low battery amps even though a voltage check can show 12-13V has a profound effect on the operation of the ECU & immobiliser. Link to comment Share on other sites More sharing options...
Benton Posted August 28, 2021 Share Posted August 28, 2021 #40As another check I disconnected the Caterham battery and hooked the wires up to my daily's battery, same result..... Switch on, gauges sweep, immobiliser light changes from slow to fast flashing...... waving tag does nothingInteresting to read in completely different thread and subject (misfiring at certain revs) possible problem with immobiliser relay, never thought of that one and not obvious to me at the time when looking around where it hides within the scuttle wiring spaghetti. Link to comment Share on other sites More sharing options...
Benton Posted September 2, 2021 Share Posted September 2, 2021 Update! So cause found ..... cream crackered immobiliser unit. New one being fitted .... more warranty parts Thanks for all the earlier investigation suggestions, at least it wasn't something I could have sorted easily myself. Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted September 2, 2021 Member Share Posted September 2, 2021 Thanks for adding the answer.Jonathan Link to comment Share on other sites More sharing options...
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