Nissan Micra bought to me after having been to 2 other garages and been diagnosed as a slipped timing chain. Has covered just 31000 miles and I thought it highly unlikely! Came to me minus rocker cover etc checked the timing and seemed to be good.
So i did the usual basic checks and no spark, found this to be the crank sensor been disconnected. A new cam sensor had been fitted. Got the spark back and found no live to the injectors. Checked relays and found the injector/fuel pump relay wasnt being switched. I earthed out the switched side and the car fired in to life!
Couple of questions, Having no wiring diagram for the car I need to know what switches the relay is it direct from ecu or is it via another relay. And If the ecu switches it does it rely on a ckp or cmp signal before it does so?
Have swapped the relay with one from another micra but its not the relay.
Does the immobiliser system on this car disable the injectors or not so could it possibly be the immobiliser? Has a nats transponder key.
No fault codes coming up at all.
Basically after saving a bit of time as I wont have to trace the whole loom back if anyone has a wiring diagram for one it would be helpful!
Thanks in advance
Dave

hi is the injection system Bosch on Nissan
according to the diagram i have from autodata the fuel pump relay is grounded by the ecu wire color black and yellow either pin 104/106 at the ecu no info for the Bosch on autodata earth 6 13 39 48 107 108 color black.
have you run a diagnostic check to retrieve any fault codes.
hope this helps martin

Dave
As the wiring diagrams are on all my info systems, which do you use ?
Kev.

Had a look on autodata im on the online full subscription and no wiring diagram! Has wiring diagram for the earlier type. Is the bosch type management system.
Is the later coil on plug type no the dizzy type.
The wire i am grounding to get it to run is white and green??
I have a bit of time on it today so im going to see what i can trace back.

looking at another diagram for the Bosch system it looks like pump trigger is off pin 1
28 34 55 and 6 are ecu ground
hope it helps its not alot of good on a print as it dosnt give wiring colors just pin outs
but that is the only one i could find for the Bosch system

Big mistake oops, Its the engine control rleay that im earthing to get everything running.
It has a permanent live to the switching side. The side that I am earthing out to make it run has just short of 5 volts running up it when relay is disconnected. Im guessing that the ecu switches this to earth to make it run?? Or is it the immobiliser that does this? Or does the ecu need imput from the immobiliser to switch it?
If I had a wiring diagram it would be so simple!!
I would of thought the engine control relay would be a switched ignition live but its a permanent live with a switched earth so assuming it goes via the ecu??
All help appreciated!!

hi lol we all done it ecm switches relay from pin 27 you are correct in you assumption about the windings permanently fed.
I did have a weird on of these a couple of years ago failed to start during testing the battery failed on the cranking test.
even though it cranked fine just refused to start changed the battery and away it went.

Do a search on this Dave, there are issues with corroded fuses on these, which have been covered here before.

Sean

Had a search but cant find much. I will have to have a look through the other forums on here to see if its covered anywhere else.
Surely corroded fuses would affect feeds?
I disconnected the ecu plug and the 5v feed still stays at the engine control relay which says to me that its switched via something else? Immobiliser possibly?
Im getting to the point where it might just get a switched earth via a relay wired in to make it run!!
Would prefer to fix properly but customer has spent money at 2 garages already and is getting a bit windy!!

Hi Dave I had the same problem as you a year ago have looked at the invoice and have described engine main relay not being earthed by ecu,carried out continuity test between relay and ecu,open wiring loom to repair broken wire,if my memory serves me correctly it wasn'nt far from the fuse box,and it would run if I earthed it at the relay,hope this helps

I have disconnected the ecu plug, there is still just short of 5v coming up the switching wire??
The switching wire goes somewhere else first I think.
Anyone know much about how the immobilisers work on these?

Just realised my multimeter is no good!!
is a 12v feed to the switching side not 5v as first thought!

You mean you have 12v at the ECU plug with the ECU disconnected? If so that would be right. The 12v would be coming from the relay coil.

I have 12v at the relay.......goes away and puts brain in.......I might actually wake up this week!!
Right ecu is not switching, pin 27 is the switch wire.
Take the relay out and it loses its 12v to pin 27.
So wiring is not at fault ecu is not switching the relay to earth.
Now when I switch the relay to earth it will fire straight up sometimes and not others. Squirt a little fuel down throttle and it fires and stays running until switched off or earth removed from the ec relay. Is this 2 faults possibly?
Left it running for twenty minutes and came up with a camshaft sensor circuit fault.
Should the ecu switch the engine control relay on when ignition is switched on or when it is cranking? I assume its just on ignition.
If its when its cranking then does it need to see a good ckp and cmp sensor signal before it will fire? Have seen it on the almeras when the chain has stretched or tensioner faulty the ckp and cmp signals go out of sync and car struggles or fails to start but never seen it on a micra before. Usually shows a faulty signal code not a circuit fault though. Or my other theory is that its not seeing the voltage back to earth from ec relay via ecu so thinks the circuit is faulty so the code is being generated by me bypassing the ecu??
Ckp and cmp have already been replaced by previous garage and giving good signals.
Or is it likely to be an ecu fault? Or earthing fault possiby?
Time to poke prod and probe methinks!

hi there pin 54 on the ecu is the switched live from the system relay the relay that is switched by pin 27.
pin 3 of cam sensor is 12v live from the system relay (pin54). pin2 of the sensor is the signal(output) form the cam sensor and that goes to pin 44 of the ecu, pin1 is earth separate not back to ecu
it would be worth checking signal from cam sensor and confirming 12v feed to sensor and ecu.
it may be looking for cam signal on start but not while running.
martin