My glow plug indicator did not light up

AbangCorp · Post by **AbangCorp** » 26 Jul 2010, 03:29

Dear Expert

I have a Xantia 1.9TD. It was all fine until I one day glow plug indicator did not light up momentarily like it must.

Check all the glow plug first, seems to give a very good reading of 0.9 & 0.7 ohm. Check the other two (where i cannot unscrew it one by one) i get another 0.8 0.7 ohm around that.

If i do my math correctly, it should be lower than 0.5 ohm.
There is not short circuited glow plug.

Check incoming voltage, no supply
So where can I start first?

Thanks

Citroen Xantia 1.9 TD '95
VIN VF7**************[VIN obfuscated, can be read by forum staff]

Post by **Peter.N.** » 26 Jul 2010, 09:58

The fact that the light is not coming on will be more to do with the supply than the glow plugs, have you checked to see if there is voltage on them with the ignition switch in the appropriate place? Could be a relay or even ignition switch fault.

The plugs should read less than one ohm but its very difficult to get a good enough connection at that resistance to get an accurate reading, if they each read less than one ohm I would say they are ok, that equated to 12 amps or maybe a little less as there is some voltage drop at that sort of current, you should have 10 - 11 volts across them in operation according to the battery state of charge.

First check the voltage across the plugs in operating mode.

AbangCorp · Post by **AbangCorp** » 28 Jul 2010, 02:54

okay, it is my incoming that gives no supply to the plug

my mechanic also tried to directly heat the plug and it did start
problem now how to rectify?

i have my schematic picture of it
some relay and stuff
but the one i concern most is the control unit

is this common having control unit to cease operation?

Post by **Peter.N.** » 28 Jul 2010, 08:48

I think the problem is most likely caused by a faulty relay, you need to check that you have voltage going into the relay and that 12v is applied to it by the ignition switch in the glow plug position, if all OK, replace the relay.

AbangCorp · Post by **AbangCorp** » 10 Aug 2010, 07:04

I am sorry if I am too blur having this wiring problem

I have the circuit already, but don't have any idea where is the relay location. Maybe I can hook up my multimeter to see from the glow plug where it connected to. This require me to open all the fuses & relay and uses it connection

Use this back trace method will spare me sometimes

haynes also have this colour code but it does not tell all the wire colour, and seem got contradicting colour to where the wire goes to

What worries me is open circuit, where i cannot back trace anymore

citroenxm · Post by **citroenxm** » 10 Aug 2010, 08:03

The Relay box is a Black Box, and on a 1995 its in one of two places, as it moved in later cars from around 1996...

Just behind the battery, theres a black cover that covers the engine fuse box, lift this away, you have then on the left the Heaterplug Black box relay, and then the fuse box next to it... The other location is behind the passenger headlight (to the RIGHT of the battery)

It sounds like this black box has given up!

If you apply volts directly to the heater plugs and the car starts, then the heaters are fine... its the Black box that could be giving you trouble.. the heater plugs are connected directly to the black box, you then have the supply wire from the heater box to a Main Large fuse infront of the fuse box..

The other plug, I think 5 pin is an earth, start acutated signal, heater plug light etc....

Hope that gives you a better idea!

Paul

AbangCorp · Post by **AbangCorp** » 10 Aug 2010, 14:59

i have checked

fuse f12 is fine (at the cockpit)

checked 2 relay you mentioned black in colour, it is now purple (i do think it is replaced before)

it is rated 25A

apply 12v and it click, immediately check the continuity pin 3 & 5 and guess what, 2 or 3 ohm for both. which is very good

coil is relay pin 1 & 2
NC is relay pin 3 & 4
NO is relay pin 3 & 5

there is 3 relay, i found out the 2

you know how? when one of the relay is not there (burnt)
it should be the other two

bingo, i also checked with haynes, yes i nailed the right
the connection between pin 1 with the other pin 1
the connection between pin 2 with the other pin 2
the middle relay which have pin 4 grounded
the other relay which have pin 1 and 3 connected

from haynes manual, it is not connected directly to black box, it is connected to pre heating control unit numbered 1150

looks like my control unit, is it the one in the box (near lhm pump) is giving its way?

citroenxm · Post by **citroenxm** » 10 Aug 2010, 15:10

Control box is the LARGER black Box...

It has a 5pin plug PLUS Two heavy duty cables on it - as I said above either Next to your Engine comparment fuse box behind the battery, under the plastic cover, or at the END OF the battery bolted to the inner wing behind headlight...

Paul

Post by **KennyW** » 10 Aug 2010, 15:50

Doi you have and engine bay fuse box as there is a fuse which is for the fuel system check if this has blown as the preheating system will not work and the car won't start.

Kenny

AbangCorp · Post by **AbangCorp** » 10 Aug 2010, 15:52

thank you citroenxm

looks like i need to find those box replacement

sorry, because i am so slow
do you mean black box is giving me problem, you immediately indicate the control unit?

my, you might have experience this so many times before

citroenxm · Post by **citroenxm** » 10 Aug 2010, 20:06

The black box is the combined Relay/Controller unit...

Ive not come accross many that have failled, but theres a first time for everything, Ive still kept every one from each car I have broken...

Paul

AbangCorp · Post by **AbangCorp** » 11 Aug 2010, 14:56

i only see timer relay, connected directly to the glow plug

i began wondering, this is not a control unit by the way
it is just a relay, you activate it and after a while stopped automotically

and haynes manual have this standard symbol, only this time it have some kind of digital signal

citroenxm · Post by **citroenxm** » 11 Aug 2010, 15:05

Exactly, thats what it is, it times how long the plugs are on for... hence the two larger wires connected to it... one goes to the heater plugs, the other to the + post near your fuse box....

This is the ONLY control box/relay for the heater plugs....

This box ALSO sends the Orange indication signal to the light on the dash board...

Paul

AbangCorp · Post by **AbangCorp** » 12 Aug 2010, 16:25

you were right citroenxm

my timer relay is burnt inside
tested, contactor does not click

seems my original use parts is also does not have this
and my mechanic ask me to modify, my circuit in my car is actually modified already

he uses only 6 pin,

one for glow plug, one for positive source
one for ground, one for bulb/indicator
and another one for signal / positive