lowlander Posted August 17, 2012 Share Posted August 17, 2012 Afternoon all, I have a problem with starting my car. The car always starts but there is occasionally a rapid clicking noise before the starter motor actually turns the engine over. Once the starter turns the engine the car starts immediately and runs fine. The problem is slightly worse when hot but there is not that much difference. The battery is fine and alternator is also working perfectly. The starter motor itself was replaced recently and the ring gear checked. As the starter motor is a pre-engaged type I am reasonably sure that the problem is electrical, however I know absolutely nothing about car electrics! Any thoughts or help much appreciated as the car is currently up for sale and I want to make sure that whatever the problem is, it is fixed for the new owner. Edited to add, I found the text below from another topic on starter motors but I'm afraid I'm struggling to understand it! If someone could explain it to me if very simple terms I would be very grateful IIRC ..... the 2.5mm brown/red cable from the MFR unit (beneath the ecu) supplies the feed to the starter solenoid - this cable doesn't always get enough current from the MFR unit to engage the starter. The relay mod is basically: Break into this cable and use the brown/red feed from the MFRU to power a separate (additional relay, 30A), combined with a negative return. The output of the relay can then be used to connect a direct feed from the battery to the remaining section of the brown/red cable running to the starter. This gives a bigger current available, and additionally reduces the load on the MFRU. Stu. Edited by - sforshaw on 9 Jul 2012 22:41:23 Johnty Lyons Yawn..... Location: One foot in the Grave Posted - 10 July 2012 21:09 Show Profile Email Poster Edit Message Quote this post in a new reply report this post Getting to the bottom of the problem was done eons ago No point in reiventing the wheel. There is too much VD across the crappy contacts in the MFRU Thus the relay mod providing a direct feed to the solenoid. Further that is not the only problem The proximity of the Starter motor solenoid to the extreme heat of the headers degrades the solenoid and its wiring All conspiring to decreasing its effeciency, and making it more succeptable to VD. A new MFRU with new solenoid and replaced wiring solves the problem until time starts the cycle all over again Thus the Relay mod A HD relay will work down to around 9volts and with HD contacts will pass a decent Volt/Amp to the Solenoid so a 6mm wire from battery to it and down to solenoid will work wonders even if nothing else is replaced and the old Br/Rd wire that used to feed the solenoid now just feeds the Relay Plus of course the MFRU is not having to pass any appreciable current.The K click has been around for more yrs than your mate has had hot dinners. I wish him all the best in his endeavours.wink smiley Martin. Edited by - Martin Young on 17 Aug 2012 16:29:00 Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted August 17, 2012 Member Share Posted August 17, 2012 There's a vast amount on this the archives. Do you know how to search... if not just say and I'll show you. IMHO there isn't a single guaranteed solution, more like a list of things to work through. What engine and starter do you have, and what type of 7 is it? Jonathan Link to comment Share on other sites More sharing options...
lowlander Posted August 17, 2012 Author Share Posted August 17, 2012 Yes, I know how to use the search function and I know that there are a number of posts on this subject but I'm struggling to understand a lot of the technical terms. I'm a complete numpty when it comes to car electrics. I have a 1994 1400 supersport with the Rover K series. Martin. Link to comment Share on other sites More sharing options...
Stationary M25 Traveller Posted August 17, 2012 Share Posted August 17, 2012 Don't use the feed from the MFRU to feed the new external 30A relay, but the supply into it from the ignition key or starter button. This then bypasses the tiny relay in the MFRU Link to comment Share on other sites More sharing options...
lowlander Posted August 17, 2012 Author Share Posted August 17, 2012 Quoting Stationary M25 Traveller: Don't use the feed from the MFRU to feed the new external 30A relay, but the supply into it from the ignition key or starter button. This then bypasses the tiny relay in the MFRU Thanks, what is the MFRU? the solinoid is on the top of the starter motor and therefore close to the underside of the exhaust primaries. Edited by - Martin Young on 17 Aug 2012 16:50:16 Link to comment Share on other sites More sharing options...
Leadership Team SLR No.77 Posted August 17, 2012 Leadership Team Share Posted August 17, 2012 Martin, basically the Rover MFRU (multi function relay unit) which is mounted underneath the ecu is not up to the job of driving the starter solenoid. It needs a secondary relay .... Firstly (as I mentioned in the text you've copied) is to break into the feed (brown/red) from the MFRU to the solenoid and insert a 30A relay. Take the brown/red coming from the MFRU and connect it to the coil side of the relay together with an earth from the battery to the other side of the coil - use black cable for this connection. Turning the ignition key to the starter position will now cause the MFRU to activate the coil in your new relay, closing the switch across the other half of the relay. This will put minimal load on the MFRU which is where the problem probably is. Now, take a new feed from the positive side of the battery (4.0mm red) and connect to the switch side of your new relay, then connect the other side of the switch to the remaining brown/red which runs to the starter solenoid. What happened previously ... turn key, relay in the MFRU closes to send high current to the starter solenoid, but in doing so overloads the MFRU and not enough current gets through. Now .... turn key, relay in the MFRU closes to send low current to the new (beefier 30A) relay, which in turn allows a high current feed to the starter solenoid directly from the battery If this fails then bypass the MFRU completely and take the feed from the ignition switch (one of the other wires going in to the MFRU but can't remember which). Stu. Edited by - sforshaw on 17 Aug 2012 16:52:56 Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted August 17, 2012 Member Share Posted August 17, 2012 MFRU = multifunction relay unit. For this purpose it's a relay to your starter solenoid. Relays are used to switch a larger current than you want to go through the controlling switch (and purposes like that). They need a feed from the switch and a big feed from the battery. When the switch is closed ("on") they allow the big current to go where it's needed, in this case the starter solenoid. Jonathan Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted August 17, 2012 Member Share Posted August 17, 2012 What Stu says. If you're not comfortable with a bit of vehicle wiring I'd suggest you don't do this on your own. Where are you? There might be someone nearby who'd come and help, or a local group. Jonathan Link to comment Share on other sites More sharing options...
lowlander Posted August 17, 2012 Author Share Posted August 17, 2012 Quoting sforshaw: Martin, basically the Rover MFRU (multi function relay unit) which is mounted underneath the ecu is not up to the job of driving the starter solenoid. It needs a secondary relay .... Firstly (as I mentioned in the text you've copied) is to break into the feed (brown/red) from the MFRU to the solenoid and insert a 30A relay. Take the brown/red coming from the MFRU and connect it to the coil side of the relay together with an earth from the battery to the other side of the coil - use black cable for this connection. Turning the ignition key to the starter position will now cause the MFRU to activate the coil in your new relay, closing the switch across the other half of the relay. This will put minimal load on the MFRU which is where the problem probably is. Now, take a new feed from the positive side of the battery (4.0mm red) and connect to the switch side of your new relay, then connect the other side of the switch to the remaining brown/red which runs to the starter solenoid. What happened previously ... turn key, relay in the MFRU closes to send high current to the starter solenoid, but in doing so overloads the MFRU and not enough current gets through. Now .... turn key, relay in the MFRU closes to send low current to the new (beefier 30A) relay, which in turn allows a high current feed to the starter solenoid directly from the battery If this fails then bypass the MFRU completely and take the feed from the ignition switch (one of the other wires going in to the MFRU but can't remember which). Stu. Edited by - sforshaw on 17 Aug 2012 16:52:56 Thanks Stu, I'll give it a try tomorrow morning.Any suggestions where I can buy the necessary materials for this mod? Link to comment Share on other sites More sharing options...
lowlander Posted August 17, 2012 Author Share Posted August 17, 2012 Quoting Jonathan Kay: What Stu says. If you're not comfortable with a bit of vehicle wiring I'd suggest you don't do this on your own. Where are you? There might be someone nearby who'd come and help, or a local group. Jonathan I'm willing to give it a go over the weekend. I'll no doubt be back on hear asking for more advice at some point! Many thanks for the (very) quick response to my questions. Martin. Link to comment Share on other sites More sharing options...
lowlander Posted August 17, 2012 Author Share Posted August 17, 2012 Quoting Jonathan Kay: What Stu says. If you're not comfortable with a bit of vehicle wiring I'd suggest you don't do this on your own. Where are you? There might be someone nearby who'd come and help, or a local group. Jonathan I live in Dunfermline near Edinburgh Link to comment Share on other sites More sharing options...
Stationary M25 Traveller Posted August 17, 2012 Share Posted August 17, 2012 You can get a 30A 12V relay from Halfords, Maplin or any car spares shop. I simply used insulated female crimp connectors on the end of single core chunky cable to press on to the four blades in the relay. Don't need a socket or anything like that. Can check on wire colours that you have to break in to if you need. Really quite simple stuff. Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted August 17, 2012 Member Share Posted August 17, 2012 If you want to do this on your own: 1 Disconnect both leads from your battery before doing any electrical work 2 Put a suitable fire extinguisher in a suitable place 3 Read a bit on the web or watch some YouTube about crimping and spade terminals etc 4 Practice cutting and crimping on a few bits of old wire before you do the real thing It's not essential for this job but you might also want to think about buying a multimeter and getting hold of the wiring diagram for your car so that you can understand what's going on. Jonathan Link to comment Share on other sites More sharing options...
lowlander Posted August 17, 2012 Author Share Posted August 17, 2012 Quoting sforshaw: Martin, basically the Rover MFRU (multi function relay unit) which is mounted underneath the ecu is not up to the job of driving the starter solenoid. It needs a secondary relay .... Firstly (as I mentioned in the text you've copied) is to break into the feed (brown/red) from the MFRU to the solenoid and insert a 30A relay. Take the brown/red coming from the MFRU and connect it to the coil side of the relay (HOW DO I IDENTIFY THE COIL SIDE OF THE RELAY?) together with an earth from the battery to the other side of the coil - use black cable for this connection. (WHAT SIZE OF EARTH CABLE SHOULD I USE?) Turning the ignition key to the starter position will now cause the MFRU to activate the coil in your new relay, closing the switch across the other half of the relay. This will put minimal load on the MFRU which is where the problem probably is. Now, take a new feed from the positive side of the battery (4.0mm red) and connect to the switch side of your new relay, then connect the other side of the switch to the remaining brown/red which runs to the starter solenoid. (WHAT SIZE OF CABLE SHOULD I USE FROM THE POSITIVE SIDE OF THE BATTERY?) What happened previously ... turn key, relay in the MFRU closes to send high current to the starter solenoid, but in doing so overloads the MFRU and not enough current gets through. Now .... turn key, relay in the MFRU closes to send low current to the new (beefier 30A) relay, which in turn allows a high current feed to the starter solenoid directly from the battery If this fails then bypass the MFRU completely and take the feed from the ignition switch (one of the other wires going in to the MFRU but can't remember which). Stu. Edited by - sforshaw on 17 Aug 2012 16:52:56 Many thanks Stu. I have a few more questions which I've added above. I've put them in CAPS so they are easier to see - I'm not shouting at you! I'm determined to give it a go. It doesn't sound too difficult (famous last words) Could you suggest where I can buy the wiring and relay? Martin. Edited by - Martin Young on 17 Aug 2012 17:30:38 Link to comment Share on other sites More sharing options...
lowlander Posted August 17, 2012 Author Share Posted August 17, 2012 Quoting Jonathan Kay: If you want to do this on your own: 1 Disconnect both leads from your battery before doing any electrical work 2 Put a suitable fire extinguisher in a suitable place 3 Read a bit on the web or watch some YouTube about crimping and spade terminals etc 4 Practice cutting and crimping on a few bits of old wire before you do the real thing It's not essential for this job but you might also want to think about buying a multimeter and getting hold of the wiring diagram for your car so that you can understand what's going on. Jonathan thanks Jonathon. Link to comment Share on other sites More sharing options...
myothercarsa2cv Posted August 17, 2012 Share Posted August 17, 2012 Just bought the parts for this on ebay. I bought a relay with a 30A fuse fitted so I don't need to faff about with another inline fuse. That plus a couple of metres of red and black wire plus postage came to £9. I'll send you a link if you like. There's a wiring diagram in the build manual IIRC, which can be found here. Link to comment Share on other sites More sharing options...
Stationary M25 Traveller Posted August 17, 2012 Share Posted August 17, 2012 Quoting Stationary M25 Traveller: You can get a 30A 12V relay from Halfords, Maplin or any car spares shop. I simply used insulated female crimp connectors on the end of single core chunky cable to press on to the four blades in the relay. Don't need a socket or anything like that. Can check on wire colours that you have to break in to if you need. Really quite simple stuff. I used Halfords 27A cable from battery to new relay to solenoid and 17A cable from battery to Relay coil. Overkill, but the bigger the better to reduce voltage drop. The relay has markings on it to show which is the coil and which terminals are the ones that are switched = feed to solenoid. Link to comment Share on other sites More sharing options...
Johnty Lyons Posted August 17, 2012 Share Posted August 17, 2012 Martin if you feel overwhelmed don't panic Electrics are not everyones cup o char. I'm at end of phone all weekend 02897542349 Link to comment Share on other sites More sharing options...
lowlander Posted August 17, 2012 Author Share Posted August 17, 2012 Quoting Johnty Lyons: Martin if you feel overwhelmed don't panic Electrics are not everyones cup o char. I'm at end of phone all weekend 02897542349 Thanks Johnty, One more question. I've looked at pictures of the fuses on the web and can see that a standard 4 pin 30A fused relay has 2 connections for the coil and 2 connections for the switch. On the connections for the switch shows a fuse. Which wire is connected to the terminal with the fuse? Link to comment Share on other sites More sharing options...
john milner Posted August 18, 2012 Share Posted August 18, 2012 A dodgy connection to a IACV might cause rapid clicking. Link to comment Share on other sites More sharing options...
lowlander Posted August 18, 2012 Author Share Posted August 18, 2012 hmmm not going too well. I did the relay mod and everything seemed to be going well. The car started fine and idled smoothly. I then decided to tidy up all the wiring using insulating tape and cable ties to make the under bonnet area look tidy. After doing all this I tried the car again and the starter motor won't turn the engine over - its completely dead. I can hear the click from the MFRU relay but nothing from the new 30A 12V new relay. I then took everything off again and checked the connections and the in line fuse - everything seemed OK. I tried by-passing the new relay and rejoining the brown / red wire but it made no difference. Is it likely that I have blown a fuse somewhere else? The lights and gauges still work. Martin. Edited by - Martin Young on 18 Aug 2012 16:15:55 Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted August 18, 2012 Member Share Posted August 18, 2012 1 Don't worry, and go and have a cup of tea and a biscuit. Walk round the block etc. 2 You've got an offer of advice from Johnty above: he's a real expert. 3 What would I do? It's good news that the car started once all after your modifications. Is everything else working except the starter? Ignition light coming on OK, and immobiliser not an issue? 4 What could have happened when you tidied up? It's probably a blown fuse, a faulty relay or a dislodged connection. You've worked that out already. Test all of those again, one at a time. Don't forget everything needs an earth circuit as well as a feed. This is where the multimeter will help. Can you borrow or buy one? Jonathan Link to comment Share on other sites More sharing options...
lowlander Posted August 18, 2012 Author Share Posted August 18, 2012 Quoting Jonathan Kay: 1 Don't worry, and go and have a cup of tea and a biscuit. Walk round the block etc. 2 You've got an offer of advice from Johnty above: he's a real expert. 3 What would I do? It's good news that the car started once all after your modifications. Is everything else working except the starter? Ignition light coming on OK, and immobiliser not an issue? 4 What could have happened when you tidied up? It's probably a blown fuse, a faulty relay or a dislodged connection. You've worked that out already. Test all of those again, one at a time. Don't forget everything needs an earth circuit as well as a feed. This is where the multimeter will help. Can you borrow or buy one? Jonathan Success! Traced the fault to a blown fuse under dash. New fuse in and it started first time! Just finished checking all the connections are tight, tidied up the new wiring and popped the bonnet back on. Going to take the car for a run and then check again. Many thanks to everyone for all the excellent advice. Martin. Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted August 18, 2012 Member Share Posted August 18, 2012 :-) Do you know the motto of medical education? "See one, do one, teach one". Now for the third level! Jonathan Link to comment Share on other sites More sharing options...
Leadership Team SLR No.77 Posted August 18, 2012 Leadership Team Share Posted August 18, 2012 Martin Stu. Link to comment Share on other sites More sharing options...
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