2002 Jetta TDI has no power to glow plug buss at startup

Not sure what "tick over" means. Suspect it is hard to start when cold? Could be bad glow plugs. They "warm" the cylinders to get them up to temp before starting. It could also be that you are not waiting for the cylinders to warm up. I have a 2009 tdi. It has a light on the dash that goes on when I put the key in, but I have to wait for it to go out before starting the engine.

Make sure the block heater is working. But with high altitude and cold air this is somewhat normal for a diesel on cold start. If the glow plug indicator light flashes off and on quickly in the dash you may also have a burned out glow plug(s), this also causes a poor cold start.

Run the plug's a couple time's instead of one. For an example on my work truck I run the plugs 3-5 even more depending the outside temp. Also I don't crank more then 20 second's. This work's even in extreme temp's such as -25F. And if you don't have the patience for this there's always starting fluid.

In addition to the 4 primary glow plugs, the cooling system also has 3 Coolant Glow Plugs to help provide extra heat to the cooling system in order to warm-up the vehicle's interior more quickly, and enhance overall engine warm-up time. (Example - Some Mercedes diesel engines use electrical heaters in the cabin because their engine is so thermally efficient.)
Likewise, this auxiliary source of heat from the 3 Coolant Glow Plugs is necessary because of the VW 1.9 TDI engines outstanding efficiency, which wastes very little heat.

The 3 Auxiliary Coolant Glow Plugs are located at the end of the aluminum cylinder head (in a protruding flange) directly below the vacuum (brake booster) pump, which also connects to a coolant hose.


The 3 Auxiliary Coolant Glow Plugs use two (underhood) relays which are monitored and controlled by the ECU. During a cold start, the vehicle's interior temperature selector switch helps the ECU choose one of three modes depending on the amount of heat required to warm-up the coolant.

For example, Coolant Glow Plug #1 can be selected to operate all by itself, or #2 and #3 can operate together as a two-some, or lastly, all three glow plugs can form a triple source of heat for maximum enhancement of engine warm-up time.

After the engine is completely warmed up and the thermostat is open, the Coolant Glow Plugs normally shut-off and remain off unless the (thermally efficent) engine cools down sufficiently to have the computer signal them to come back on to keep the engine and cabin air warm. Extensive idling times at stop lights or in the driveway are scenarios where these glow plugs are most likely to recycle on and off.

In conclusion, the period of Preglow and Afterglow is determined by the engine's coolant temperature (during a cold or hot start), which helps the ECU select a predetermined time-cycle for the combustion chamber and / or Auxiliary Coolant Glow Plugs to follow.

Finally, one myth that needs to be immediately debunked, is the belief that the TDI's advanced Glow Plug System is linked to the opening of the driver's side door, which is false! It is also noteworthy to mention that some earlier VW diesel glow plug systems were operated in this manner, but not so with the advanced VW Jetta 1.9 TDI engine.

There is a 5th injector called the cold start injector, that is electrically controlled off the starter. You can easily unscrew it while still attached to hoses and wires, and watch it squirt. You can also verify it is getting voltage with a test light or meter. There is also a thermal timer for it that could be bad and preventing current from the starter.

* Do NOT do this on a warm/hot engine. Aluminum threads strip easily*

Pop off the top engine cover

Now, right in front of you you'll see the big fat injectors with the fuel lines attaching them. Just under this all are what look kinda like tall skinny spark plugs with a plastic buss attached to them. These are the glow plugs.

Pull off the buss bar from the plugs one by one, it might take some removing of the flexible fuel lines. and just pull the buss bar out of your was a bit.

Get a deep 10mm socket and an extender and remove the plugs.

When installing the new plugs start them as far as you can by hand w/ socket and extender- don't crank em in there.

Make sure they are more than snug but DO NOT OVERTIGHTEN

If you wanna go all the way torque plugs to 11 ft-lbs

....don't forget to re-connect any fuel return lines you may have removed

glow plugs have absolutly nothing to do with the car not going over 20 mph. sorry, but you gotta keep on em. at a guess i would say it was due to them doing a t-belt and not setting the timing right somehow. but that's just a guess.... while I love my TDI, the service and parts at most VW dealers are at the bottom of the list

yes glow plugs have a lot to do with engine having tough
time in cold weather. before replacing glow plugs
check relay and fuses.

this is a common problem for these cars glow plugs go bad like spark plugs however the smoke would lead to bad mass airflow meter. it is not telling ecu corrcet miss. disconnect mass airflow meter. when cold see if this makes it start better. it should would means you need new m.a.f. glow plug issue take a test light place clamp on positive of battery then pull off glow plug connectors place tip of test light on glow plug the bad one will have a dull light unlike the good one which will be brighter. will need new plugs and wire harness four **** connectors and wire striper and crimper will fix concern good luck

Ok , ok. Give me some more information and we'll solve this. We're talking about a jetta TDI 2000 with an ALH engine code I figure.
#1 Do you have an faults recorded in the ECM like a check engine.
#2 Are you using synthetic oil 5W40 preferably Castrol?
#3 How old is your fuel filter?