Mini Cooper S ECU Issue (I bet know one can help)

[Jonathan English]

Hi guys,

Im new here and desperate for some help, I have posted this on multiple mini forums and the car has also been to multiple garages and an auto electrician. I am based in Essex if any of you guys are local and need some work! I have a cooper s with an issue and need help, as im not getting any luck on the mini forums yet anyway.... I have owned mini now for 12 weeks (5 weeks working 7 weeks and counting broken). However my sister today went to take it for a drive and see how it compares to her S. She started it up and instantly the battery light came on. I had driven it for 40mins to her house with no problems, stopped for an hour, then started it again. I thought it was weird but I said drive it anyway must be a dodgy battery or the alternators broken maybe. We drove for around 30secs and battery light went off. 2mins later engine light come on with the EML light. We pull over and the cars in limp mode. I tell her to turn it off and we started it back up at this point melting plastic smell and a bit of smoke comes through the passenger side vent area (I assume a wire has shorted somewhere?) We turn it off leave it for 5 mins and start it back up... No warning lights, no smell, absolutely fine... So we drive it back to hers... I get in it to go home and again start it and it's fine get 20mins up the road and it jumps into limp mode I pull over turn it off and start it again EML light goes out but the check engine light stays on.... I drive the remaining way home with the light on.

So i book it into a garage... they cannot connect to the ECU (all garage including myself can connect to the various modules via the port but NOT the engine modules to read fault codes), and recommend specialist with main dealer software, again they cant read it but recommend another garage, they have changed the battery, the alternator, and the replaced the ECU with a new cloned ECU.... Still not working and still not possible to connect to the ECU.... They recommend taking it to a tuning specialist.... and the good news is.... they cant fix it either.... So far i have spent, nothing at the first, (they told me they didn't have the technology for it) £20 at the second for a diagnostic, 470 at the 3rd + parts (alternator, batteryand ECU £450) and the fourth its cost £240 they also cannot find the problem, they have checked continuity on all ecu wiring, they have checked all the obd wiring, and cannot find anything, they have removed (some) modules, they even remove the k line wire and ran another wire to the appropriate port on the ecu, and still nothing, just as all the other garages... they again can read all modules except the engine codes.

The ECU light comes on whenever there is significant load, 1 week before the problems above i had an 18% pulley fitted and a larger intercooler, this i believed was bringing on the EML light on whenever you put your foot down, however, the next garage noticed that the crank pulley had split (4 garages did not notice this and one of them fitted the alternator and did not notice!)... this is what was causing the EML and has since been fixed and now the car runs and drives fine again which is great, however, the obd port still does not connect to the ECU.

I personally, have now stripped down the dash, I have power on pin 16 of the OBD and resistance on pins 4 and 5 and i get approximately 3.5v on pin 7. I have double checked for chaffing on the wires through the bulkhead, the grommet is in perfect condition and I cannot see any issues. Worth noting all fuses are fine also. from this point onward i am at a complete loss. The company that cloned the ECU could read the ECu fine on the bench, the original and the cloned both allow the car to run and drive they just cant be connected to.

If there is anyone that has any idea, please help me out

Thanks,

Jon

 

[Gazthesparky]

Hard to say without being in front of the car.

But this is a long shot I had a similar problem with my Audi a few years back.

My Audi wouldnt start every now and again and when I tried to connect to the engine ECU with the software it couldn’t find it. I thought that the ECU was goosed but stripped the car down to find that it was a faulty power relay. The relay provided power to ECU and if it wasn’t activating it wasn’t providing power to the ECU

So just a stab in the dark check for a power relay providing power to the ECU

 

[Jonathan English]

Hard to say without being in front of the car.

But this is a long shot I had a similar problem with my Audi a few years back.

My Audi wouldnt start every now and again and when I tried to connect to the engine ECU with the software it couldn’t find it. I thought that the ECU was goosed but stripped the car down to find that it was a faulty power relay. The relay provided power to ECU and if it wasn’t activating it wasn’t providing power to the ECU

So just a stab in the dark check for a power relay providing power to the ECU

Hi Mate,

Thanks for the reply! I will have alook and see if there is such a thing on the mini. I do however have one question... Did the audi run and drive fine even though there was no power to it? The problem I have is that for all intents and purposes, the car is perfect, just this stupid issue! I will have a google and see what i can find

Thanks for your help,

Jon

 

[static zap]

Still sounds like ,communications coming thru from ECU is getting blocked , may be by another device hogging the line .(or you have a devious short/damaged wiring /missed in buzzing out )
_Still worried did you find what burned up -- fear its wiring damage_

 

[Jonathan English]

My assumption was that it was the crank pulley failing and the belt slipping, caused the smell, although i cant tell this... 3 of the garages (and myself) have checked and cannot find any burning, also worth noting that the communication issue predates the burning aswell.

 

[SparkyChick]

If the cable is part of a loom (assuming it's wrapped in that fluffy fabric tape they seem to use these days), it doesn't have to appear burned to have smoked.

An overload could cause sufficient heating for smoking but not ignition. This may be very difficult to spot, especially if it's in a loom.

I would go through the fuse box and check all the fuses to ensure they are the correct rating and that none of them have blown.

 

[Jonathan English]

Hi Mate,

Thanks for your reply, again the garages (and myself) have all fuses in all the of the fuse boxes, according to this thread here they are correct. I have also changed all fuses that relate to the ECU/Canbus/K-Line just in case the fuse was faulty. I have also checked the wiring at the back of the main fuses box just in case the wiring had come loose.

thanks

Jon

 

[static zap]

Is it 2002 2006 model ,has a user way of seeing some data , via button presses ?
(and resetting all sorts--may include Comms data rate )

 

[Jonathan English]

Yea its the 2006 model. you can reset various bits you are correct, however the problem I have is that I am building it as a track car andits tuned as far as it can be without remapping.... Essentially to tack it to the next stage (cam, head, uprated supercharger etc.) but i need to be able to tune the ECU to go further, which obviously means the OBD port needs to work.

Thanks

Jon

 

[static zap]

Would be interested in results of "1.3" if dash is behaving !
MINI Cooper ECU Reset Procedure - R50/52/53 MINIs - https://new.minimania.com/ECU_Reset_Procedure___R50_52_53_MINIs

 

[Gazthesparky]

Yes my Audi did run normally. The relay was intermittently working so when It worked the car would run normally with no fault codes. As soon as the power relay failed the car wouldn't start. It would turn over but wouldn't start. As if there was a flat battery. If you scanned the the car it wouldn't find the engine ECU and log that as a fault. This was because there was no power powering the Engine ECU and hence the software couldn't talk to the ECU . I replaced the relay and the problem disapeared. I cannot say for sure in your case but it sounds similar to mine. might be worth checking if there is a relay powering the engine ECU.

 

[Eliot]

Hi guys,

Im new here and desperate for some help, I have posted this on multiple mini forums and the car has also been to multiple garages and an auto electrician. I am based in Essex if any of you guys are local and need some work! I have a cooper s with an issue and need help, as im not getting any luck on the mini forums yet anyway.... I have owned mini now for 12 weeks (5 weeks working 7 weeks and counting broken). However my sister today went to take it for a drive and see how it compares to her S. She started it up and instantly the battery light came on. I had driven it for 40mins to her house with no problems, stopped for an hour, then started it again. I thought it was weird but I said drive it anyway must be a dodgy battery or the alternators broken maybe. We drove for around 30secs and battery light went off. 2mins later engine light come on with the EML light. We pull over and the cars in limp mode. I tell her to turn it off and we started it back up at this point melting plastic smell and a bit of smoke comes through the passenger side vent area (I assume a wire has shorted somewhere?) We turn it off leave it for 5 mins and start it back up... No warning lights, no smell, absolutely fine... So we drive it back to hers... I get in it to go home and again start it and it's fine get 20mins up the road and it jumps into limp mode I pull over turn it off and start it again EML light goes out but the check engine light stays on.... I drive the remaining way home with the light on.

So i book it into a garage... they cannot connect to the ECU (all garage including myself can connect to the various modules via the port but NOT the engine modules to read fault codes), and recommend specialist with main dealer software, again they cant read it but recommend another garage, they have changed the battery, the alternator, and the replaced the ECU with a new cloned ECU.... Still not working and still not possible to connect to the ECU.... They recommend taking it to a tuning specialist.... and the good news is.... they cant fix it either.... So far i have spent, nothing at the first, (they told me they didn't have the technology for it) £20 at the second for a diagnostic, 470 at the 3rd + parts (alternator, batteryand ECU £450) and the fourth its cost £240 they also cannot find the problem, they have checked continuity on all ecu wiring, they have checked all the obd wiring, and cannot find anything, they have removed (some) modules, they even remove the k line wire and ran another wire to the appropriate port on the ecu, and still nothing, just as all the other garages... they again can read all modules except the engine codes.

The ECU light comes on whenever there is significant load, 1 week before the problems above i had an 18% pulley fitted and a larger intercooler, this i believed was bringing on the EML light on whenever you put your foot down, however, the next garage noticed that the crank pulley had split (4 garages did not notice this and one of them fitted the alternator and did not notice!)... this is what was causing the EML and has since been fixed and now the car runs and drives fine again which is great, however, the obd port still does not connect to the ECU.

I personally, have now stripped down the dash, I have power on pin 16 of the OBD and resistance on pins 4 and 5 and i get approximately 3.5v on pin 7. I have double checked for chaffing on the wires through the bulkhead, the grommet is in perfect condition and I cannot see any issues. Worth noting all fuses are fine also. from this point onward i am at a complete loss. The company that cloned the ECU could read the ECu fine on the bench, the original and the cloned both allow the car to run and drive they just cant be connected to.

If there is anyone that has any idea, please help me out

Thanks,

Jon

Hi Jon Iv been experienceing exactly the same problems with my recently purchased r53. Going into limp mode on hard acceleration. But unable to communicate with engine Ecu but will communicate with all other control modules. So I’m unable to read any codes so stabbing in the dark as to why it’s going into limp mode. I will check the crank pully tomorrow as that seems like a common problem but still won’t be able to communicate with the engine and like you I have plans that will require mapping. So basically have you got to the bottom of this yet and if so can you help please.

 

[plugsandsparks]

1. Another stab in the dark. It would be worth while getting your hands on the full Mini wiring diagrams for all the modules. You will then see how many can buses there are. I have been stripping out a Cayman for example and they have a separate can bus for the engine, called Can Drive, there is one for the dash CAN Display, one for diagnostics and one for heating/lighting, thats 4 in all and of course has the K line out of the ECU. There is a gateway box that enables comms between the CANs. Also the ODB port does not connect directly to the engine CAN , however when i wanted to put CAN data onto the video for revs and throttle position i connected directly into CAN Drive, rather than the K line or Can diagnostics at the OBD because i wanted a direct connection. Once you find the right wires for the ecu CAN you may find the ECU CAN either directly off the ecu wiring harness or the ABS controller. You could then hook up a dummy OBD port just with ECU CAN and try and talk to it directly.

 

[Eliot]

1. Another stab in the dark. It would be worth while getting your hands on the full Mini wiring diagrams for all the modules. You will then see how many can buses there are. I have been stripping out a Cayman for example and they have a separate can bus for the engine, called Can Drive, there is one for the dash CAN Display, one for diagnostics and one for heating/lighting, thats 4 in all and of course has the K line out of the ECU. There is a gateway box that enables comms between the CANs. Also the ODB port does not connect directly to the engine CAN , however when i wanted to put CAN data onto the video for revs and throttle position i connected directly into CAN Drive, rather than the K line or Can diagnostics at the OBD because i wanted a direct connection. Once you find the right wires for the ecu CAN you may find the ECU CAN either directly off the ecu wiring harness or the ABS controller. You could then hook up a dummy OBD port just with ECU CAN and try and talk to it directly.

Thanks I will see if I can get a wiring diagram off auto data and go from there. But if I’m honest it sounds a little in depth for me. As I wouldn’t know what pins would need what voltage ect and how to produce a smaller voltage for example Iv heard some of the obd pins only have 3.5v. Thanks again I was kind of hoping Jonathan was going to reply with a simple fix lol.

 

[plugsandsparks]

Its easier, maybe, than it sounds. The wiring diagram should give you the PIN nos and there is 12V, earth, K line and CAN high and CAN low. You dont produce any signals, you just bring them to the OBD port with wires. To add telemetry to the video i used the wiring from an unused stability sensor that i knew was connected to engine ecu.
Again an ECU tuner knows this and provided you can show him the engine CAN wires, he should be able to connect his cable directly in. First though you need diagram to get the colours, CAN cables are a twisted pair and look similar to speaker wires