Locating Glow Plug Relay. VW Sharan TDI 1.9 ?????

[Wayne Cardall]

HI I'm new to the forum and would appreciate any help. I have a VW Sharan 1.9 Diesel TDI Diesel Mk1 that only seems to start after a couple of idle days. I was initially advised to get a new battery but this did nothing to help. After speaking speaking with someone who had a similar issue with their Ford Galaxy apparantley it might be worth changing the glow plug relay to solve the problem. I'm completely at a loss trying to locate it and would appreciate any help.

Thanks. Wayne...

[johnnyroper]

I would be more inclined to go with relay 109,this is ecu/injection power supply relay,common problem on diesels.

It will be in fuse box but you will need to drop it down to access,have a look in ref library for info on finding it

[Wayne Cardall]

Thanks johnnyroper.

  I've read on other google search posts referencing the glow plug relay saying something about relay 103 ??   Apologies I'm not really savvy regarding electrical issues is the relay 109 a completely different relay from the 103? i.e. does this solely supply the icu/injection power supply as opposed to the 103 ?

Apologies once again I know this might seem like a basic question but electrics are my Kryptonite. Thanks for the help.

[johnnyroper]

103 is glow plug relay.
However I can't see it is your problem as even if glow plugs do not operate the engine should still start eventually especially during warmer months,it would probably start lumpy and smoking.
To not start I would guess at 109 stopping feed to ecu.

Only cheap to buy new relay so worth a try as fairly easy to swap over once you have accessed the relay panel above fuse box.

[Wayne Cardall]

Thanks Johnnyroper.

Really appreciate your help, will give it a go as like you said its quite a inexpensive part. 

Cheers for the help !!... 

[Chrispb]

Hi Wayne
What year is your car?
Your right in saying relay 103 is the glow plug relay but as johnnyroper says 109 which is the power relay for engine ECU is a more likely culprit.
Glow plugs have little effect on starting this time of year.
Have a look at the small LED light on the drivers door, what is it doing when your trying to start the car, does it flash while cranking or stay on solid.

[Wayne Cardall]

Hi Chris
Y reg which I believe is 1991
The car is parked a couple of miles away from me at the minute to check the LED, to be honest I didn't even know of it's significance.
When it doesn't start it makes a steady clicking noise when trying to crank it over, not sure of the significance.

[Chrispb]

Y reg means your car was registered between 1st March 2001 and 31 August 2001
This also means you have a PD engine and will have an electric fuel pump fitted in the tank as well as a mechanical pump driven by the engine.
The electric pump can fail intermittently which can also give a non start, clicking relays can also be low battery voltage.

[marcushamblin1976]

In my experience no glow plug light and no start on these engines is usually relay 109 voltage supply relay for engine control unit.  103 is the glow plug relay.  No power to 103 is caused by no supply from 109. Relay 109 supplies power to

- Glow plug relay



ECM

Fuel quantity adjuster



Cold start injector

Waste gate bypass regulator valve (N75)

Change over valve (N239)

EGR vacuum regulator valve (N18)

Mass air flow sensor (G70)



Clutch vacuum vent valve (if equipped)

Brake vacuum vent valve

Relays for preheating coolant (if equipped)

Crankcase ventilation heating element

The ECM supplies power (and sometime ground as well) for:

Fuel cutoff valve

Cruise control switch

Manifold (intake) air pressure/Intake air temperature sensor

Needle lift sensor

Engine speed sensor

Engine coolant sensor

Closed throttle position switch (part of "go" pedal)

Kickdown switch (part of "go" pedal)

Throttle position switch (part of "go" pedal)

Fuel temperature sensor

Modulating piston displacement sensor

The ECM also communicates to the instrument cluster electronics and transmission control module (on automatics).

As a result of this, you can see why if the relay starts to cause power to flicker, or voltage drops, for all of these components, the results can be "unpredicatable" and none of them desireable.

Sent from my SM-G930F using Tapatalk

[Wayne Cardall]

Hi All

UPDATE:

I changed the 109 relay and initially I thought this was the culprit.  When the car starts which still seems to be sporadic at best it runs fine until a warning light shows " STOP CHECK COOLANT SERVICE MANUAL "  Once this appears and the engine is turned off i'm then back to square one where the car needs to wait another day or two before it starts.

Coolant levels are fine, and the cars temperature while running registers at a stable temperature. Not sure if this might be a Thermostat problem or sensor .

any advice would be appreciated

[johnnyroper]

I think the coolant check is a bit of a red herring as the engine will continue to run if no coolant in it until such point as it distorts head,there is no start or run inhibit for lack of coolant.
From those symptoms it still sounds like a supply is lost to the engine ecu,I know you replaced 109 but have you had a volt meter on the relay output when fault occurs likewise also check the coil has 12v. It could be whatever supplies 109 with its switch on voltage that is causing this,at a guess I would say it's from ignition switch putting a switched feed in to fuse box that powers 109 amongst other stuff. It's going to be a case of tracing the circuit back and seeing where feeds are lost with this fault I reckon.

[johnnyroper]

Did you replace relay 109 with a new part and was it grey or black?

[johnnyroper]

Sorry another question when you have the issue does the engine turn over on starter and fail to fire up or it's just completely dead?
Might also be worth checking the ground points for corrosion etc,stick a meter on earth at relay coil and measure ohms to earth on body,you want as close to 0 as possible.
Also do you still have the clicking sound when fault occurs?