micra 998cc 1999 when you turn heater blower on the engine will stop dead !!!! will only restart if you remove key and wait for red nats light to flash, then starts up no prob. Does not stop all the time but about 1 in 10 OPERATIONS of switch . All heater speeds work . If you set off in car with heater blower on car will stop but only at slow speeds.If you set off with blower off and switch it on at speed it stops the engine AND will not restart till key is removed and nats light has activated not nice in third lane m62 !!!!!!!
heater blower on engine stops micra
- Thread starter td valentine
- Start date
pollyp
Club Member
please write sentences with punctuations. I can't hardly understand it.
now, normally whenever the fan motor is turned on at any speeds, a signal is sent to the ecu informing bout the increased load. the ecu would then open the Idle Controller Valve to increase the rev slightly to compensate for the increased load of the resister card on the alternator.
if the ecu isn't informed of the load or the IACV is seized closed or base idle is set too low (particularly during cold starts) and neutral switch is off (in gear), then there may not be enough throttle to sustain idle and it stalls
now, normally whenever the fan motor is turned on at any speeds, a signal is sent to the ecu informing bout the increased load. the ecu would then open the Idle Controller Valve to increase the rev slightly to compensate for the increased load of the resister card on the alternator.
if the ecu isn't informed of the load or the IACV is seized closed or base idle is set too low (particularly during cold starts) and neutral switch is off (in gear), then there may not be enough throttle to sustain idle and it stalls
thing is it will stop the engine, by that i mean cut it out as if you have turned off the ignition key at 70 mph not just tick over !! if i turn on all lights wipers heated window hazards to load up current needed at tickover it does not stop engine .. only the heater blower has this affect
middle
just started
had a week of running no problem then did it 3 times, to restart you have to wait for nats red light to come on and the petrol pump to stop and then it will restart if pump continues to run IT WILL NOT start . removed heater card it looks ok going to try it like that with card removed one speed motor thanks for your reply
it will stop at any speed will not restart till nats light comes on in dash and petrol pump has stopped running ie primed had a week of no probs then 3 instances in as many miles baffled thanks for your help
pollyp
Club Member
does it give a hint of firing up during cranking with the fan motor on?
cos during START, the ign switch dedicates all electrical power to only the demanding starter and ecu/engine systems, everything else (heater fan, stereo etc) is temporarily disconnected until u release the key back into IGN.
if she fires up during START then the ecu/loom/fuel/ign sysem is working fine. if not, then part of the ecu/loom/fuel/IGN system is preventing the engine from working. flashing eng light usually indicates nats is triggered.
if she fires up but then stops (and dash lights remain on) when the key goes back into IGN (accessaries circuit reconnected) then check for any blown fuses, fan motor not seized/shorted, stereo not shorted
if she starts up then stops when u release the key and all the dash lights etc are off, the ign switch would be stuck inbetween START / IGN.
try apply very slight anti-clockwise pressure on the key after she fired up to help encourage the ign switch to return to IGN mode, but before reaching ACC mode.
if that works then the switch is worn or gunked. remove and clean the inside contacts or replace with newer switch if worn
cos during START, the ign switch dedicates all electrical power to only the demanding starter and ecu/engine systems, everything else (heater fan, stereo etc) is temporarily disconnected until u release the key back into IGN.
if she fires up during START then the ecu/loom/fuel/ign sysem is working fine. if not, then part of the ecu/loom/fuel/IGN system is preventing the engine from working. flashing eng light usually indicates nats is triggered.
if she fires up but then stops (and dash lights remain on) when the key goes back into IGN (accessaries circuit reconnected) then check for any blown fuses, fan motor not seized/shorted, stereo not shorted
if she starts up then stops when u release the key and all the dash lights etc are off, the ign switch would be stuck inbetween START / IGN.
try apply very slight anti-clockwise pressure on the key after she fired up to help encourage the ign switch to return to IGN mode, but before reaching ACC mode.
if that works then the switch is worn or gunked. remove and clean the inside contacts or replace with newer switch if worn
rig
the car will either fire up and run or spin over and over without a hint of firing . drive down road at any speed turn on heater fan and the car engine will stop as if the ignition has been turned off !! it went for a week without bother than did in 3 times is quick succession . to restart you have to turn off ignition wait for nats light to come on flashing and listen for fuel pump to stop and its relay to click then it will restart . the heater blower works on all speeds i have now removed the heater resistor card and iam going to see how it behaves now . the blower only works on full i have tried waggling key loose connections etc its only the heater that affect it
thing is i have switched everything on lights hazards all wipers heated rear screen eveything to load up the draw on electrics but it does not stop it !!! its never stopped when blower is off . i think its the first click on the heater blower switch that causes problem is that when the resister card will be drawing most current ?? i put a meter to the plug that feeds the heater motor and it showed 12.5 volts no matter what setting the blower switch was on. how does the card work ??
go with that ?
eng cuts out like switching ignition of ? thats the ign switch failing ..(or related system?)
only the heater blower should be changed then or it might be worth unpluging ? to test
removed heater card so i only have full speed and going to try that , as it seems to be the slower speed when you turn blower on that causes it , is more current drawn? when the resister card is being used to regulate heater to slow speed ??
will try it with card out and see what happens
done a 30 mile round trip with heater blower on then off no probs but still not confident of car its for my daughter to use when home from university so it needs to be right
had a run out today everything fine blower on and off thought it was fine , then turned it on at 50mph cut out !!!! took a few turns on /off with ignition pump running cont and eml flashing before it would start . once started eml kept flashing . once home stopped it waited till nats light came on and pump stopped and restarted eml light went off running fine . it needs mot in feb so i think mot first . then invest in a ecu from fusion
had new issue!! stalled car would not restart . fuel pump running cont turned ign on off wait for nats light to come on ,then listen for pump , after about 5 mins of this pump finally stopped running and it started ran fine with eml light on 5 miles down road turned heater blower on and it stopped got it started again using same procedure . stopped for petrol came out and it would not start same as when i stalled it . BEEN OUT again TODAY did 60 miles no probs heater used on all speeds. i had looked at ecu and found it bolted in slack thinking earth issue? tightened it up. thought i have cured it !!!! WRONG !! STOPPED CAR AT DESTINATION LEFT IT FOR 45MINS came to it would not start pump running cont tried ign on off waiting etc etc had to call RAC . spark at plugs no earth feed to injectors . BAD weather and darkness coming in,so recovered it home 4 me . got home car started first turn !!!!!! .wish it had not as a continuase fault is easier to fix !! NEXT DAY STARTED no prob stop it and it will sometimes restart but most times not . leave it for 30 mins and it will start MUST be nats problem ???????????????????
ECU ORDERED FROM FUSION WILL let you all know the outcome pretty confident its nats ??? or some sort of witchcraft !!!!!!!!!!!!!!!
ECU FITTED !! car started and restarted took it for mot 8 mile round trip and it passed NOT TAXED at moment but i think its cured the problem a good run out and a stop start will be the final test IF YOU GET A PROBLEM LIKE THIS YOU COULD CHANGE THE ECU KEY CHIP RECIEVER ETC WITH ONES OFF THE SAME SCRAP CAR . but its a load of chew plus you still have the nats that could come back to haunt you its one less thing to let you down if its removed
it appears to be fingers crossed !!!!!!!!!!!!
did 50 miles stop start no prob so i hope its sorted it will keep you posted thanks to ed at fusion
used car a few times, first time starting, heater blower not stopping engine !!!!!!!!!!!!!!!!! hopefully its cured ????????????? can reccommend ed at fusion for the ecu mod hope it keeps going daughter has a 800 mile round trip to scotland planned at easter !!!!!!!! hope it does not happen !!!!!!!
used car a few more times ECU from ED at FUSION seems to have done the trick
