Intermittent Starting issue

Hi all, I have a 300tdi EDC and all of a sudden its developed a problem in which when i turn the key, nothing happens. All lights on dash do there normal things etc just not turning over. It will do this a few times then fire up no problem but not always. Also sometimes when I turn the key it might take a second or 2 to start turning over, is this an ignition problem or further?

Its not an immobiliser issue because when its immobilised it turns over fine, just the fuel is cut.

Thanks in advance

I hate to state the obvious that you've probably already ruled out, however is it a battery issue? Mine was giving me wipers and headlamps but not enough to turn the engine due to a faulty/poor condition battery.

It did sometimes start turning over but couldn't quite crank it.

Have you got a jump pack? Just to rule it out.

No worries, sorry I should have said. Battery is great, I use the red top Optima and when it cranks, it does it with power

Delwyn said:

No worries, sorry I should have said. Battery is great, I use the red top Optima and when it cranks, it does it with power

Click to expand...

Ah okay, good good.
How's the earth? Solenoid?

Hopefully someone more knowledgable on the newer vehicles will be along soon.

I need to double check all earths but I re strapped them about 8 months ago. Which solenoid?

Thanks for your help

Guess he means starter motor solenoid. Small spade terminal to that can get loose and corroded.

That's great thanks

You can do a ghetto test on the starter solenoid by bridging across from the big threaded terminal that has the thick battery cable running to it, to the little spade terminal which is the ignition “trigger”, energised when the key is in the start position. Use a chunky screwdriver with a well insulated handle to bridge the terminals. It will spark when you do this. Don’t panic! You don’t need the ignition on for this test but if you want to start the engine using this method then you do need the ign on.
You may need to remove some turbo pipe work to get access to the terminals on the starter motor.

By doing this, the starter should turn, proving that it and the solenoid are working as they should. If the starter still doesn’t turn, the solenoid is probably faulty but can be replaced without buying a new motor.

To test the motor itself, bridge the 2 threaded terminals. This will bypass the solenoid and the motor should turn

Simply fitting a new female spade terminal onto the trigger wire cured my issues.


Iirc the trigger wire to the spade connector is white. Pull it off the terminal before doing the test. Make sure the vehicle is in neutral too (you only make this mistake once) or the vehicle will lurch rather spectacularly!!

I’m tired but hope this makes sense!!

Thanks for the replies on this. I have taken the starter out and it seems to work just fine when connecting a jump starter to it, red to end terminal, black to casing and them jumping red and spade, all works well.. When testing the positive from the battery you get 12v+ and also the little space connector gets 12v+ when the key is turned to the start position. It just seems to get more confusing as time goes on!

300Tdi EDC means D1 Auto, yes? Check the start inhibit circuit on the AT - you might achieve something by rocking the AT selector...

Also ignition switch OR the starter relay, if fitted, could be allowing voltage, but not enough current to energise the starter solenoid.

Best option is to download RAVE and to have a look through the relevant electrical diagrams to do some proper trouble shooting.

Good Luck.

Thanks for that. Yes Auto D1 is correct. The solenoid is being energised as you get a very positive click then you turn the key coming from the starter which I guess is the solenoid being activated. I presume the click or clunk is the solenoid firing the dog cog forward?

300 Tdi uses a pre-engaged starter motor where the starter solenoid engages the bendix in the ring gear of the flywheel, and then connects power to the motor to spin the motor shaft..( that's the theory anyway - it's not 100% which is why the bendix is spring loaded - but it reduces wear on the ring gear to almost nothing )

It sounds as though your fault is within the electrical end of the solenoid - it's probably full of carp - a good clean out might improve the situation. The solenoid can also be replaced on it's own. It might be that the brushes in the motor are sticking - so a good clean out here too...

OK cool, I have taken the cap off and cleaned out inside where brushes are etc. Can you take the solenoid apart or only off and replace?

It can be taken apart, but needs crimping back together. IIRC, RTC4978 (?) is about £15 - so hardly worth the effort. ( check the part number fits yours ! ) Also worth searching to see if there is a repair kit like there is for the D2 starter ( NAD101240KIT ).

thanks for that

New starter motor and fuel lift pump and it starts brilliant. I guess I will never find the issue but I replaced the starter, Lift pump and re-did all earths, I am happy again now