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glow plug light always on - 638

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malcolm@mill.me.uk

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Vito 114 tourer 2015: Vito 108d 97: 108d 98: Traveliner 2003 ; Aixam; z1100; xbr500; z440 ++++
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Discussion starter · #1 ·
I've had the problem, so have dozens more.

correct operation:-
turn ignition on, glowplug light comes on and goes out within 2 seconds...... ok

On ALL the time:-
with NO interuptions i.e ignition on, light comes on permanently....... 2 or more glowplugs, or relay (next to radiator) faulty..... it doesn't do anything apart from correct operation if only ONE glowplug is faulty........ commonly the thick red power lead to the relay has snapped off from its mounting screw

ON briefly:-
(goes out within 2 seconds) then comes on AGAIN and STAYS on...... the immobiliser has operated.... normally a door has been opened or the ignition tried with the wrong key...... it is ONLY clearble with star diagnosis as it tells you someone tried to steal it (the official reason).......
A weird trick..... I found out by accident.... unplug the cables from the air sensor in the middle of the pipe that goes across the top of the engine (about 3inch diameter hard pipe).... drive it.... it should be in limp mode.... you need a few miles at enough revs for the limp mode to operate....... reconnect everything........... this often cures the "fault" because of a "backdoor" in the ecu programming......... it also works on a few other warnings.

malcolm
 
#2 ·
No freakin way, that should save a lot of people money when the MOT comes round with the new rules. I always had this problem but the van started sweet all the time. Stupid.
 
#3 ·
Mine passed the MOT today with that light on, it didnt even get a mention in the advisory section, I will try disconnecting the sensor and see if it works, interestingly when plugged into the snap-on diagnostic machine it says something like glow plug output failure, but checked and changed the module and had 4 new glowplugs and didn't cure it, deleted the code and the light went out but came back on within 10 seconds,
My light came on originally after a carwash day at work when someone tried starting it with the wrong keys, I hadn't put the two together until now, I'll see if it works, cheers
 
Discussion starter · #4 ·
obviousl I can't guarantee it working on your 638 but its worked on all the ones I've tried...

its only the glowplug light on diesels that is used for 2 different warnings...

the idea is that when the immobiliser operates, its because of an "illegal" attempt to steal the vehicle.... if it was easily reset, the "thief" could hide the attempt..... it does make sense

because the controller uses the same memory for other faults, it can be forced to overwrite the immobiliser fault memory.... it shouldn't happen but it does.

warning lights are NOT part of the mot.... UNLESS they indicate faults in the "safety" circuits e.g abs, braking, traction control

the abs circuit has a self test... it lights with the ignition and goes out within 2 seconds... if it doesn't light or it stays on, the mot will fail...... the same applies to brake testing circuits (the vito only checks fluid level and pad thickness)

its an annoying light... nothing more... thanks to the guy at the factory in darkest germany (I was linked from maastrict so have no idea who I was speaking to) who told me of this "error"

malcolm
 
Discussion starter · #6 ·
there are numerous ways to induce limp mode... basically ANY engine or brake sensor, the one I said about is simply that its the most convenient.

the brake wear lead is a common cause of limp.... one runs down the bottom of the front shocker and loops to the brake pad..... its so exposed that it frequently damages.

the "fix" is that the limp fault is stored in the same bit of memory that the immobiliser code is stored.... so it simply overwrites it............ it shouldn't happen but it does on some memories.. it depends on the version of hardware and storage fitted.

malcolm
 
#7 ·
I have a problem with mine. The light does not come on until after it is started and goes out after about 60 seconds. What is this?
 
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#8 ·
I've got a similar issue with my '05 115 dualiner 639. Starts fine, lights go out and then glowplug light comes on for about 60 seconds.

Do you reckon same procedure could work for this?

Thanks
 
#10 ·
malcolm@mill.me.uk said:
I've had the problem, so have dozens more.

correct operation:-
turn ignition on, glowplug light comes on and goes out within 2 seconds...... ok

On ALL the time:-
with NO interuptions i.e ignition on, light comes on permanently....... 2 or more glowplugs, or relay (next to radiator) faulty..... it doesn't do anything apart from correct operation if only ONE glowplug is faulty........ commonly the thick red power lead to the relay has snapped off from its mounting screw

ON briefly:-
(goes out within 2 seconds) then comes on AGAIN and STAYS on...... the immobiliser has operated.... normally a door has been opened or the ignition tried with the wrong key...... it is ONLY clearble with star diagnosis as it tells you someone tried to steal it (the official reason).......
A weird trick..... I found out by accident.... unplug the cables from the air sensor in the middle of the pipe that goes across the top of the engine (about 3inch diameter hard pipe).... drive it.... it should be in limp mode.... you need a few miles at enough revs for the limp mode to operate....... reconnect everything........... this often cures the "fault" because of a "backdoor" in the ecu programming......... it also works on a few other warnings.

malcolm
Click to expand...
I follow your instruction and it got into limp mode(rev lock at below 2500rpm), then i reconnect the air sensor. I continued driving and nothing change. I felt like it got out of limp mode, but the glow plug light still lit. I want to know if i should stop the engine and turn the key off before reconnecting the cable or not.

Thank you in advance.
 
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