mark_w Posted February 19, 2018 Share Posted February 19, 2018 Hi all Since I've owned my car 2001 R500 K the radiator fan has not been working as the temp rises. it has a dash override switch that I use and the fan comes on from here ok . It has a brown ecu temp sensor in the water rail along with what looks like a switch these have the wires attached. So just looking for some pointers on how to get the fan to come on in the normal way. Thanks Mark Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted February 19, 2018 Member Share Posted February 19, 2018 Can you add a photo of the sender and switch? Do you have a multimeter? If there's only one wire attached to the sender turn on the ignition and touch that wire to earth, eg the block: does the fan come on?Jonathan Link to comment Share on other sites More sharing options...
mark_w Posted February 19, 2018 Author Share Posted February 19, 2018 Yes can do pics tomorrow , and I do have a multimeter, two wires to the brown plug and two to switch Link to comment Share on other sites More sharing options...
Wrightpayne Posted February 19, 2018 Share Posted February 19, 2018 On my 1.6 K, the fan sender is in the top tank of the radiator - joining the two wires together should make the fan kick in. If it doesnt then its a wiring fault. If it does then I'd substitute the sender.Ian Link to comment Share on other sites More sharing options...
SM25T Posted February 20, 2018 Share Posted February 20, 2018 In the water rail the sender with one wire feeds the temperature gauge, the one with two wires feeds the ECU. On my car the fan thermo switch is in the top of the radiator. As above ... with ignition on, unplug the connector and short across the connector contacts. If fan doesn't run, check the fuse and the fan. If it does run, check the temperature rating of the switch... It will be marked on it with open and closed temperatures ... 92/86 for example. Check also that there is no air in the top of the radiator as it won't trigger it if not immersed fully. Some cars don't use this thermo switch, but a signal from a more upmarket ECU. Link to comment Share on other sites More sharing options...
SM25T Posted February 20, 2018 Share Posted February 20, 2018 It maybe your thermo switch in the rad has too high a rating .... It is a readily available part from any car parts shop. You don't want the fan running all the time, but you do want it to cut in to prevent overheating. I changed my water thermostat on the engine from 88C to 82C to help keep things cool ... And I think my thermo switch is closing at 92C. Link to comment Share on other sites More sharing options...
mark_w Posted February 20, 2018 Author Share Posted February 20, 2018 thanks for the replies, so have a few things to check now will try shorting the contacts, see pic for the plug and switch,there is not a switch in the rad . could this be the ecu controlled version? Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted February 20, 2018 Member Share Posted February 20, 2018 Some cars don't use this thermo switch, but a signal from a more upmarket ECU.there is not a switch in the rad . could this be the ecu controlled version?More, please, Ian. This looks pretty central to sorting this. Was that as they came from the factory or a subsequent modification? Does the associated switch ring any bells?mark_w: What's the history of the car... was it used for racing etc? Has the cooling system been modified?Jonathan Link to comment Share on other sites More sharing options...
SM25T Posted February 20, 2018 Share Posted February 20, 2018 Don't start shorting those contacts. That comment only applied to the thermo switch in the top of the radiator ! The smart ECU os something like an Emerald which can be looked into and parameters adjusted with a laptop. That is the extent of my knowledge on such devices. Link to comment Share on other sites More sharing options...
SM25T Posted February 20, 2018 Share Posted February 20, 2018 The focus isn't ideal on the senders in your photo. The big brown one should be the temperature input to the ECU. The other one looks a bit chunky from the view we have to be the gauge sender ... That normally has only one wire. So it may be a fan thermo switch .... but I haven't seen one fitted there before. Need some input from those with R500K Link to comment Share on other sites More sharing options...
mark_w Posted February 20, 2018 Author Share Posted February 20, 2018 yes used as a hill climb car by the previous owner, but don't know if the cooling system is modified in any way although doesn't have a heater fitted and override is heater fan or heated screen switch on dash cant remember would need to look later Link to comment Share on other sites More sharing options...
mark_w Posted February 20, 2018 Author Share Posted February 20, 2018 thanks understood re the shorting only other pic i took this morning Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted February 20, 2018 Member Share Posted February 20, 2018 Thanks, Ian.It would be nice to work out what it currently has and why... but how about fitting the usual sender to the radiator? Can you find the original wire that would be connected to that?Have you got an appropriate wiring diagram? Please send me a PM if you'd like a copy.Jonathan Link to comment Share on other sites More sharing options...
SM25T Posted February 20, 2018 Share Posted February 20, 2018 Well that definitely looks like the fan thermo switch to me. In that case you can unplug the separate connectors and touch them together with the ignition on ... to make the fan run. Link to comment Share on other sites More sharing options...
TomB Posted February 20, 2018 Share Posted February 20, 2018 Agree with Ian, that's a thermo fan switch. Weird place for it though by the clutch fork? Wouldn't you want a radiator fan switch to somewhere near the radiator? Link to comment Share on other sites More sharing options...
mark_w Posted February 20, 2018 Author Share Posted February 20, 2018 when zoomed in to pic the 2 wires looks green/blue and black , only looked on the wire diagrams on here under guides so thanks Jonathan PM sent Link to comment Share on other sites More sharing options...
mark_w Posted February 20, 2018 Author Share Posted February 20, 2018 Touching the two wires from the switch together didn't start the fan so checking the voltage across the wires and get a reading of 6.3 v. Although did momentarily flick to 12.5 v as the ignition key was turned on then steady at 6.3vnot sure about the override switch as doesn't look like it is wired in the conventional way as works whichever fuse I remove So that's a bit of a concern , Link to comment Share on other sites More sharing options...
SM25T Posted February 20, 2018 Share Posted February 20, 2018 All sounds a bit of a mess. Maybe time to try and trace the wires between the fan, fuse, override switch, thermo switch and earth connection at fan ... installing new cores as required Link to comment Share on other sites More sharing options...
David.Ashley.Poole Posted February 20, 2018 Share Posted February 20, 2018 Hello Mark,i have a lot of (unwanted) experience in tracking lost cables... In the US I have a 2002 Morgan Plus 8 and there is absolutely no documentation on the car from MMC. Mind you, it is beautifully built in a hand-constructed sort of way. LOL.So I use a cable tracer that I bought from Home Depot, the US equivalent of B&Q. It generates an RF output modulated with an audio warble, and you use alligator clips to attach the output to the cable in question and ground, and then use a proximity tracer wand to find the route and other end of the cable. I find it quite invaluable, for everything from failure resolution to ECU sensor analysis to what fuse does what investigations. In the U.K. I have a CSR, and there are a couple of unused cables emerging from the loom at the engine bulkhead that I want to trace. There are lots of these tracers on Amazon UK from about 20 UKS up - and I will buy one next Spring when I return, but I do not have any recommendations yet.It sounds to me as though the previous owner of your car could (or did) not fix the problem and added the dashboard switch as a solution... but it seems possible that the thermostatic switch may not even be connected. So I would start with a signal trace at the dash switch, then follow up from the fan, and finally the thermostatic switch, and see what is connected to what. And then, as the song goes, you will be able to say “I can see clearly now...”(!). Let us know if you buy one and how you get on. Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted February 20, 2018 Member Share Posted February 20, 2018 Wiring diagrams sent, Mark.NB all: there is a specific diagram for the main harness for the R500 K with Stack dash. I don't know how it differs.Jonathan Link to comment Share on other sites More sharing options...
mark_w Posted February 20, 2018 Author Share Posted February 20, 2018 Thanks all . So sounds like I have a bit of work ahead of me but the cable tracer sounds a great help. Thinking it was probably a quick fix with the override switch , will report back on here when I have an update thanks for the wiring diagrams Jonathan Link to comment Share on other sites More sharing options...
Wrightpayne Posted February 20, 2018 Share Posted February 20, 2018 On the normal K, installing an override switch usually bridges the two terminals on the fan sender. Physically tracing those wires back may help.Ian Link to comment Share on other sites More sharing options...
David.Ashley.Poole Posted February 21, 2018 Share Posted February 21, 2018 Hello Mark,i have a lot of (unwanted) experience in tracking lost cables... In the US I have a 2002 Morgan Plus 8 and there is absolutely no documentation on the car from MMC. Mind you, it is beautifully built in a hand-constructed sort of way. LOL.So I use a cable tracer that I bought from Home Depot, the US equivalent of B&Q. It generates an RF output modulated with an audio warble, and you use alligator clips to attach the output to the cable in question and ground, and then use a proximity tracer wand to find the route and other end of the cable. I find it quite invaluable, for everything from failure resolution to ECU sensor analysis to what fuse does what investigations. In the U.K. I have a CSR, and there are a couple of unused cables emerging from the loom at the engine bulkhead that I want to trace. There are lots of these tracers on Amazon UK from about 20 UKS up - and I will buy one next Spring when I return, but I do not have any recommendations yet.It sounds to me as though the previous owner of your car could (or did) not fix the problem and added the dashboard switch as a solution... but it seems possible that the thermostatic switch may not even be connected. So I would start with a signal trace at the dash switch, then follow up from the fan, and finally the thermostatic switch, and see what is connected to what. And then, as the song goes, you will be able to say “I can see clearly now...”(!). Let us know if you buy one and how you get on. Link to comment Share on other sites More sharing options...
anthonym Posted February 21, 2018 Share Posted February 21, 2018 R500K here, bit late to this party, but mine works fine (so there is hope), previously with standard ecu and now with emerald ecu. If you still need info I can explore my setup .. as far as I vaguely recall, the temp comes in at 84 degrees.. and is via the ecu, not a sender in the rad. I think also I may have replaced it at some point (during 15 years so a bit hazy). R500K has of course a Stack ST8130 display (I'm assuming they all do) so here's a copy of the manual . You mention it was a hill climber, which is a very short event, so I can't help wondering if the previous owner increased (or disabled?) the "fan on temp" to avoid loss of horse power because a minute or so extra heat just generates even more power... the Stack control buttons may not be in the "right" order on the dash, mine aren't.in fact now wondering if that's why you have the over-ride switch.. the extra power question.what do I suspect? The sensor sender, maybe a mod to disable it switching on the fan .. does it work at all other than manually?anthony p.s. the above is ALL from memory..pps just re-read your op: sounds to me like it's disabled on purpose. Link to comment Share on other sites More sharing options...
simon_h Posted February 21, 2018 Share Posted February 21, 2018 That looks like a stack coolant temp sender to me. Would explain why it didn't do anything to the fan and has a ~5v feed Link to comment Share on other sites More sharing options...
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