charlie_pank Posted January 6, 2006 Share Posted January 6, 2006 Apologies in advance for the rambling post. EU3 K series with FIA switch, starter button and relay mod. I have starter motor problems when hot. Whenever I hear the dreaded 'click' I get out my spare bit of cable and make a direct connection from the (+) terminal of the battery to the solenoid, at which point the car ALWAYS starts. I have replaced the FIA switch, done the relay mod and still have the problem. Therefore I have decided that the fault lies in the wiring/connections either between the (+) of the battery and the starter relay, or between the relay and the solenoid. I have done a bit of digging with my multimeter and found that the resistance between the (+) term. of the battery and pin 30 of the starter relay is 9.1 ohms and the resistance between pin 85 and the solenoid is 0.9 ohms. Therefore the total resistance when starting the normal way (and everything is cold) is 10 ohms. I measured the resistance of the 'fly lead' I use and found it to by 1 ohm. Therefore I guess that I get 10x the current when I use the fly lead, which is why it works! What I can't figure out is where this resistance is coming from: 1) Resistance from Batt --> Term on starter motor (which feeds all the brown power wires for the whole car) = 1 ohms 2) Resistance From Term on starter motor --> pin 30 = 9 ohms 3) Resistance of brown wires running under starter motor .8 ohms So 8.2 ohms of resistance are lurking somewhere in the wiring loom between where the brown wires enter the loom and pin 30 of the starter relay. Can anyone shed any light on where this resistance is coming from, and how I might fix it? Link to comment Share on other sites More sharing options...
F355GTS Posted January 6, 2006 Share Posted January 6, 2006 Charlie Does the EU3 still use an MFRU? if so I'd suspect that, having said that if you have the relay mod then I can't see why it would have any real bearing, in that assuming the relay switches it is connecting your fly lead from starter direct to battery negating any of the original loom. If you are gettign excessive resistance in the mdded circuit then it should be easy to replace the wire/ modification relay Mark Link to comment Share on other sites More sharing options...
charlie_pank Posted January 6, 2006 Author Share Posted January 6, 2006 I'm pretty sure I could fix the whole thing by running a new wire straight from the (+) rail to pin 30, but I want to know where in the loom this massive resistance is coming from. What happens to the brown wires inside the loom - where do they go? Link to comment Share on other sites More sharing options...
F355GTS Posted January 6, 2006 Share Posted January 6, 2006 Charlie I think I'm right in saying that Brown is unswitched unfused power, in theory it comes direct from the Battery so perhaps it's worth checking your FIA switch? Mark Link to comment Share on other sites More sharing options...
charlie_pank Posted January 6, 2006 Author Share Posted January 6, 2006 There are two brown wires that come off the big terminal on the starter motor. It looks like one goes to the FIA switch (to get switched off I suppose). No idea where the other one goes. I measured the resistance between the brown wire at the FIA switch and pin 30 and found about 5 ohms which still seems like a lot to me. The FIA switch itself doesn't seem to be offering a great deal of resistance. Link to comment Share on other sites More sharing options...
F355GTS Posted January 6, 2006 Share Posted January 6, 2006 Charlie ignore what I posted here if you've read it, I need to rethink! Edited by - F355GTS on 6 Jan 2006 21:44:55 Link to comment Share on other sites More sharing options...
charlie_pank Posted January 6, 2006 Author Share Posted January 6, 2006 Right, following more investigation, I have found that the (+) terminal is connected to pin 30 of the starter relay via the following route: START: BATTERY 1) Big fat red cable to FIA switch 2) FIA switch 3) Big fat red cable to terminal on starter motor 4) Brown wire to FIA switch 5) Brown wire to ECU fuse 6) ECU fuse 7) Purple wire to insulated spade connector in centre of bulkhead in engine bay 8) Insulated spade connector 9) Brown wire to ??? END: PIN30 I have measured the following resistances: BATT--> ECU Fuse: 1.1 ohm ECU FUSE 1.0 ohm ECU FUSE--> INSULATED SPADE: 0.9 ohm INSULATED SPADE --> PIN 30: 0.9 ohm So I'm expecting a total of 3.9 ohms of resistance between the battery and pin 30... Because when the FIA switch is 'off' everything is earthed through a big fat resistor, the only way to measure Batt --> Pin 30 is with FIA switch 'on'. It was at this point that my multimeter battery ran out, so no more action 'til tomorrow, however, I think it may be the case that the resistance in the last area (insulated spade --> pin 30) rises dramatically when the FIA switch is 'on'. Could this be something to do with the ECU being powered up? Is there something in stage 9 which increases the resistance massively? Dad says that my ohm-meter can't measure resistance when there's current flowing from the car battery. Tomorrow, when I've got a new meter-battery I'll start again measuring voltages. Edited by - charlie_pank on 6 Jan 2006 22:48:10 Edited by - charlie_pank on 7 Jan 2006 00:01:32 Link to comment Share on other sites More sharing options...
LazerBrain Posted January 6, 2006 Share Posted January 6, 2006 Charlie - As you are measuring quite small resistances with your meter, you will probably need to take into consideration the resistance of the meter leads which could be upto an ohm. Touch the meter leads together and take a reading - then subtract this value from your other readings. ie if the meter leads are 0.5 ohm, then your ECU fuse reading is actually 1.0-0.5 = 0.5ohm You should also be measuring the resistance from the battery end of the big, fat, red cable with the battery disconnected. cheers, Darren. Link to comment Share on other sites More sharing options...
charlie_pank Posted January 7, 2006 Author Share Posted January 7, 2006 Ta, I'll do that tomorrow. Does anyone have a wiring diagram for the engine loom? The only one I've got stops at the purple wire that is the 'Engine Loom Power Feed', and it's precisely from this point on that I need to see what happens! C Link to comment Share on other sites More sharing options...
LazerBrain Posted January 7, 2006 Share Posted January 7, 2006 Ah, the beauty of BlatChat... 😬 Myles posted a link on one of my threads earlier, which has an EU3 engine loom diagram. here click on 'Techy Things', 'Wiring diagrams for Caterhams' then there's a PDF link near the top. cheers, Darren. Link to comment Share on other sites More sharing options...
Mick Day Posted January 7, 2006 Share Posted January 7, 2006 Try here for the engine loom itself. Although based on the VVC wiring there are common componants with EU2 & EU3 based non VVC engines. Link to comment Share on other sites More sharing options...
charlie_pank Posted January 7, 2006 Author Share Posted January 7, 2006 Right, so I've now disconnected the battery + and - and then measured the resistance between the + batt cable and pin 30 of the relay, to find virtually none. So I've written myself a list of things to test with my multimeter when I'm actually experiencing the failure. I have a 'fly lead' permanently wired in to the solenoid terminal, which I just touch against the + of the battery to start when all else fails, I'll be very interested to measure the voltage between this lead and the + terminal of the battery when the starter button is depressed but failing to actually throw the solenoid... Link to comment Share on other sites More sharing options...
Normans_Ghost Posted January 8, 2006 Share Posted January 8, 2006 Charlie, I haven't read all the above. I have posted several times about a problem of high resistance on the LT side of the solonoid. The wire is routed past No 4 branch of the exhaust. This wire gets "cooked" inside. From the outside it looks OK but if you splice it open where is passes the exhaust you'll find it's burnt brown/black. I recommend cutting this wire out and using male/female connectors at the point above the bell housing fit a new peice of wire of heavier gauge than the original and route around the back and below the starter so it's shielded from the exhaust. The reason for heavier gauge is that it will take longer to bake and with male/female spade connector in line the wire is easy to replace next time. The cars I've done this to at Le Mans have had 6v at the solonoid and the wire crumpled away when cut. Maybe david W can explain what the relay mod does as it won't cure this problem. Norman Verona, 1989 BDR 220bhp, Reg: B16BDR, Mem No 2166, the full story here You and your seven to The French Blatting Company Limited Link to comment Share on other sites More sharing options...
Mick Day Posted January 8, 2006 Share Posted January 8, 2006 The relay mod cures the problem caused by the existing relay in the MFRU (multifunctional relay unit?). There are 4 relays in side: starter motor solenoid; lambda heater; fuel pump & injectors. The theory is that the starter relay contacts pit very easily & produce too high a resistance etc. Bypassing this relay with an external relay helps to solve the problem. Running the solenoid wire inside some heat resistant sleeving helps a bit but look on the wire & relay as annual consumables for best reliability. Link to comment Share on other sites More sharing options...
Normans_Ghost Posted January 8, 2006 Share Posted January 8, 2006 Mick, now you mention it, I did wrap a inch or two of (expensive) cool tape around the wire where it went near the exhaust. got to careful with cool tape as it's metallic. Someone refered to it as one of my bodge jobs, but short of replacing the whole loom what else would you do? Norman Verona, 1989 BDR 220bhp, Reg: B16BDR, Mem No 2166, the full story here You and your seven to The French Blatting Company Limited Link to comment Share on other sites More sharing options...
charlie_pank Posted January 8, 2006 Author Share Posted January 8, 2006 I cut the LT relay wire where it comes out of the loom and put a spade on it. I cut the spade off the other end of it too. Then I took the sleeve off and ran a new wire along next to it and cable tied them together. I soldered the old and new wires together and put a new spade on at the solenoid end. I put a spade on each wire at the loom end. I've attached both of these spades to a switch along with the spur from the loom, so that I can switch between old and new. I wrapped the whole of this spur in tin-foil and then in black electrical tape to try and protect from the heat a bit. I've left the switch on 'old' at the moment. The next time I go for a blat I'll get the car nice and hot, then try and start, if I have the usual problem, I can whip the bonnet off, flick the switch and try starting again, to prove that it's the cable that's at fault. I'll let you know what happens. Link to comment Share on other sites More sharing options...
charlie_pank Posted January 15, 2006 Author Share Posted January 15, 2006 First chance I've had to go out and test, and the b****** thing still doesn't work. I have learned a little more information, so I'm hoping that someone who understands these things better than me can help: Tested the resistance of all the bits of the circuit that I could and found no 'bottlenecks'. I found that the voltage drop from the starter relay to the spade on the solenoid was only about 0.8v so that's not the problem. I discovered that holding down the starter button for about 5 seconds caused the 20A ECU fuse (which also powers the starter solenoid) to blow. 'Right' thought I, 'must be a massive internal resistance in the solenoid itself'. However, using the 'fly lead' to power the solenoid from the(+) term of the battery directly still threw the solenoid and spun the starter instantly. So do I simply need to use a beefier fuse? Link to comment Share on other sites More sharing options...
Normans_Ghost Posted January 15, 2006 Share Posted January 15, 2006 Charlie, I'm a bit confused on what you've done. Try feeling along the solonoid wire. If should be flexible (try any other wire and see how easy it bends). Now, where the solonoid wire goes close to No. 4 manifold, does if feel more rigid?. If so the cut it out completly and use a new piece of wire from the starter to the joint at the bulkhead. I suggest using male/female spade connector so it can be easily replaced in the future. Other than that and assuming 20amp is the correct rating I'm stumped and it needs a first hand look. Norman Verona, 1989 BDR 220bhp, Reg: B16BDR, Mem No 2166, the full story here You and your seven to The French Blatting Company Limited Link to comment Share on other sites More sharing options...
charlie_pank Posted January 15, 2006 Author Share Posted January 15, 2006 Cheers Norman, I have replaced the wire as you suggested, I kept the old one there too, and put in a switch where the spur comes out of the loom so I can switch between 'old' and 'new' easily. So I've got two wires, wrapped together running from the toggle-switch up at the loom down under the starter and both going into 1 spade which plugs into the solenoid. There is a third wire also soldered into the spade that feeds the solenoid, which runs up under the starter with the other two and is wrapped around the chassis rail, so that when all else fails, I can touch it straight onto the (+) of the battery - this I am calling the 'fly-lead'. When the engine was hot and I got the dreaded 'click' I did a few things including: 1. Try switching from 'old' to 'new' - no difference 2. Measured the voltage drop from the starter relay to the end of the fly lead whilst pressing the starter button (I don't want to get up-close and personal with the exhaust while it's all hot, so this is the best measure I can think of to figure out if there's a problem with the wiring to the solenoid). - no major resistance found, regardless of whether using 'old' or 'new'. 3. Disconnected battery and measured the resistance between the (+) battery lead and the starter relay - no major resistance found. 4. As previously mentioned, holding down the starter button causes the relay to click to complete the circuit and you can hear the solenoid trying to throw too, but hold it for more than a couple of seconds and the current blows a 20A fuse. However, the fly-lead connection to the battery still works every time! Link to comment Share on other sites More sharing options...
charlie_pank Posted January 17, 2006 Author Share Posted January 17, 2006 Right, so I've decided that it's a marginal problem in the solenoid/starter that is only not working when it doesn't work - therefore the extra kick it gets from being connected directly to the battery overcomes this marginal problem. So I've got the solenoid & starter out of the car and on the kitchen table. I've got the solenoid off and clearly the plunger etc could do with a clean, but I'm also interested in the switch that powers the starter motor: 1. Is there anyway to get the black plastic end off the solenoid so I can examine the switch itself? 2. The post that the plunger pushes to activate the switch seems quite difficult to depress for the first bit of travel, then really difficult to move for the last bit. Is this normal? 3. One of the big contacts (can't remember which one offhand as I'm at work now) has a metal ring around it attached to the black plastic case with a blob of solder on, what's this for? 4. With all the bolts removed the two big post contacts rattle about - is this normal? Link to comment Share on other sites More sharing options...
charlie_pank Posted July 5, 2006 Author Share Posted July 5, 2006 I have fitted a new solenoid. Still have the problem. So far I have done the following: 1) Relay mod 2) Replaced LT wiring to solenoid 3) Replaced FIA switch 4) Replaced solenoid Every time I have the problem, the car ALWAYS starts if I connect the solenoid straight to the battery, so I know I have no problem there. As far as I can see it I have 2 possibilities left: 1) I seem to remember someone talking about a problem with the FIA switch earth resistor, can anyone shed any light on this? 2) Replace the fat red wiring from battery-->FIA switch-->alternator IDEAS PLEASE - I'm starting to despair!!!!! Link to comment Share on other sites More sharing options...
Alan Bowler Posted July 5, 2006 Share Posted July 5, 2006 Nothing much to add other than: - I never had the problem until the FIA switch was (professionally) fitted - problem seemed a bit better after I fitted the relay mod, and replaced the "cooked" wire, but I still got a click when engine was very hot last week. Was going to clean the solonoid next, but not sure I'll bother now. I agree, it does seem like a "marginal" problem. My gut feeling is that the relay mod/new wire just reduce it for a while. - I wonder if this problem can be narrowed down to being (generally) FIA switch related (i.e. how many people only started getting the click after fitting a switch?) - Will fit a fly lead now, for those "stuck on the forecourt and no bump starters available" moments. AB Link to comment Share on other sites More sharing options...
fevans Posted July 5, 2006 Share Posted July 5, 2006 Morning Charlie. I have been through all the stages you have and ultimately it was the starter motor at fault, even though you seem to have identified the cause as being wiring related. Caterham have a new upgraded 'standard' motor (Magneton) with an internalised solenoid for £130, which is supposed to solve the problem. I decided to splash out on one as I was beginning to dread using the car and being stranded somewhere. It immediately solved my problems, and a lot of us are hoping it will prove reliable in the long term. Do keep a couple of relays in reserve as well (they are after all cheap and easy to swap)as they can develop faults. Mine did. Having replaced everything in the starting system, it is all going to be heat shielded, and the exhaust primaries fully wrapped. Best Regards Felix Yealmpton Link to comment Share on other sites More sharing options...
Tony Whitley Posted July 5, 2006 Share Posted July 5, 2006 I fitted the relay mod and a new Magneton starter with a new wire soldered to the terminal instead of relying on a spade connector in all the carp but still had problems and like you a direct connect to batt + would start it every time. My bodger's answer to this was to fit a second relay between batt + and the solenoid and touch wood that's cured it Link to comment Share on other sites More sharing options...
charlie_pank Posted July 5, 2006 Author Share Posted July 5, 2006 It can't be a problem with the starter motor, the solenoid, or the spade connector to the solenoid, as the fly-lead works every time and is a semi-permanent fitting into the same spade connector. :( Maybe I need to replace the relay AGAIN. Link to comment Share on other sites More sharing options...
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