Fabia 1.2 HTP Starting problems

[simion_levi]

I'm normally in the Octavia forum, but our Fabia has just developed a problem and its a bit of a headscratcher. (1.2 HTP 2009)

 

As of yesterday it completely fails to start/turn over, no movement or sound from the starter yet all other electrics are working OK. However, the main possibilities have already been checked and eliminated;

It will bump start OK, starts and runs fine

I can jump 12V to the solenoid on starter with ignition switch on - starts and runs perfectly fine

 

My conclusions:

Battery is fine

Starter is fine

Main supply/earth cables to starter, battery, engine must be fine, since I can get it to start with a cable to the solenoid

(Do please point out any errors in my reasoning!)

 

So as far as I can see, it must be something in the ignition switch to solenoid circuit that is the problem? I know the MK1 Fabia had a reputation for broken solenoid signal cables - yet I still seem to have 12V at the solenoid wiring connector when I hold the key in ignition position. I've tried a short cable between both sides of the wiring connector just to eliminate contact problems and that doesn't work.

 

Help!

[simion_levi]

Just to expand on next steps and help I actually need, if you see no fault in the conclusions above -

 

I can only suppose that the ignition signal wire/circuit is still the issue. 12V may be showing on the multimeter, but perhaps it cannot supply sufficient current for the solenoid to activate?

 

I'd like to understand how the ignition circuit works. Is there a relay for it somewhere, and/or does the ignition signal pass through the ECU? Any wiring diagrams or advice would be greatly appreciated!

[Breezy_Pete]

1 hour ago, simion_levi said:

I can only suppose that the ignition signal wire/circuit is still the issue. 12V may be showing on the multimeter, but perhaps it cannot supply sufficient current for the solenoid to activate?

 

That would be my guess, is there any sign of cracked insulation on the wire, near the entry of the connector?

 

From memory, the ignition switch has one output that takes 12V to the solenoid down that wire, and another output which goes to engine ECU to tell it that cranking is (should be) happening.

 

[Phil866]

My sisters Fabia Mk3 had a similar problem when it was only a few months old, The Cardiff dealer struggled to solve the issue (it was intermittent) and called in a Skoda expert. It turned out to be the battery post terminal clamps had not been secured properly at the PDI. Cleaned and tightened and never a problem since. I hope your issue is as easy and cheap :-). 

[simion_levi]

 

13 hours ago, Phil866 said:

My sisters Fabia Mk3 had a similar problem when it was only a few months old, The Cardiff dealer struggled to solve the issue (it was intermittent) and called in a Skoda expert. It turned out to be the battery post terminal clamps had not been secured properly at the PDI. Cleaned and tightened and never a problem since. I hope your issue is as easy and cheap :-). 

 

I wish it were that simple! Unfortunately, it does start without any hesitation if I replace the starter signal wire with a flying lead and touch the battery.

 

19 hours ago, Wino said:

 

That would be my guess, is there any sign of cracked insulation on the wire, near the entry of the connector?

 

From memory, the ignition switch has one output that takes 12V to the solenoid down that wire, and another output which goes to engine ECU to tell it that cranking is (should be) happening.

 

 

Not particularly! The Elsawin wiring diagrams appear to show a direct connection to the ignition switch, so I should probably take the steering wheel and trim off and see if I can run a temporary cable from the switch to the solenoid.

[Breezy_Pete]

May not need to remove the wheel, but I don't know my way around the cabin trim panels of a mk2.

[mrgf]

As you reasoned the battery is fine, I assume you tried jump starting from another battery/vehicle with just battery to battery connections? It should still fail to start!

Edited 5 July, 2018 by mrgf

[simion_levi]

Yes, initial recovery effort was to jump, which failed, so had to bump start to get it home. By any metric I can think of, the battery is fine - it is consistently starting the engine without any issue when I give the starter solenoid 12V directly, rather than through the ignition switch cable. The troubling thing is that I can see 12V on the ignition cable - and can power a small load (sidelight bulb!) with it - but it must not be passing enough current to activate the solenoid.

 

It could be that I cut back a few inches of cable and bridge the wiring connector and it would work, but I'm reluctant to start chopping up the loom now just to find the problem is actually further back - e.g. ignition switch, or supply to the ignition switch.

 

I've pulled the steering column top cowl off and undone the screws for the bottom, unfortunately the wheel does need to come off to be able to extract it! Buggers..

[Breezy_Pete]

Have you tried a pull test on the solenoid connector? If it's all in good condition you should be able to tug connector against cable held a few inches away and not bust anything.  If it has an area of corroded copper within the insulation somewhere in that area, a pull may well show you exactly where.

[simion_levi]

It was the ignition switch - jumping the supply cable to solenoid cable at the switch connector plug worked perfectly, yet a key turn through the switch was obviously not contacting sufficiently for the current required.

 

The replacement is a cheapy no-brand, so half-wondering if I should swap over (to e.g. OE or Hella) in the not too distant future. For the moment though, I am glad to say it is resolved. I just have to put the car back together now!

Edited 6 July, 2018 by simion_levi

[Breezy_Pete]

Well done, and thanks for letting us know where the fault lay.