Dear all,

 

I have an issue on my MK1 2002 1,4mpi where the power steering pump decided to not work anymore after i started it.

 

What happened:

 

I drove to work and everything was working fine. When i started it later I immediately didn't have power steering anymore.

It did not return when I made several corners and drove on the highway etc. All this happened yesterday.

Then today I diagnosed alot, turning enigine on/off clearing ecu faults several times, battery on/off (see below). All of a sudden when driving to work it worked again. Untill I turned the engine off and on again the powersteering failed again and didnt come back anymore.

 

What i diagnosed:

 

Reconnected powersteering pump connectors on the pump itself.

Checked fluid level --> OK

Scanned the ECU for faults (with vagcom/delphi and ELM dongle) --> No faults except for some general error saying "Control module failure, check wiring", When i cleared it it didnt come back anymore

Checked the fuses --> Interior fuse 7 and engine bay fuse 3 are both OK. Though im not 100% confident the interior fuse is the correct one. My legend doesnt have a clear picture of anything powersteering related.

 

Im kind of running into a dead end here. At first I thought the pump was broken and i was about to order one untill it started working again for that brief moment, this would indicate that at least the pump and motor are not broken.

 

Kind regards,

 

Jarno

 

 

Have you checked the fuse strips on top of the battery? They can develop very fine cracks and make intermittent contact.

 

Example...

 

Edited 3 October, 20196 yr by TMB

Yes i checked them, even loosened the bolts on them, they seem to be fine, ill check them again to be sure.

You need a full Autoscan of all fitted modules or you need to scan just the PAS module for faults. Module 44, Steering Assist, under the Chassis tab in VCDS.

 

The PAS system is often the first casualty of a charging system or battery fault, so check that your battery light comes on with ignition, and the battery terminals are tight. Clean up the main earth point behind the battery while you're at it.

 

Steering angle sensors are a weak point too, which is why a proper scan is a great starting point. Was it just the engine ECU you could talk to with your kit?

My delphi didnt scan specific modules, which it normaly does, and vcds didnt work properly, though i think if i scan just module 44 it might work, thnx ill trh that tomorrow too along with the terminal and voltage checks

I'd suggest checking the battery or just replace it. It's getting colder which is usually the time a battery will first show issues AND as the power steering requires lots of current that is usually the first thing to show up as a problem.

Edited 3 October, 20196 yr by bigjohn

Ill add swapping the battery from one of the other cars into it to the list 😁

Actually a dodgy angle sensor will not cause the PAS to completely stop working, it will put the PAS light on but the PAS will still work.

 

I strongly suspect a failed pump unit, a bad battery or charging system.

Working on the car as i write this message,

swapped out battery

Cleaned terminal to the chassis

Read out ecu module 44

 

No results, though i was able to get a PAS code on the central electronics.

 

This suggests the communication between the main ecu and the pump electronics is bad. Code 01309

 

Check the Ignition 12V and CAN wires near the four-way plug of the PAS module, including unplugging the connector and examining for water ingress and corrosion.

Edited 4 October, 20196 yr by Wino

I jnplugged all an reconnected, i measure a healthy 14v on the big plug. No succes

Problem seems to persist no matter what i do or check. The dfm connector seems to be absent for me. When i track the signal wires from the alternator they follow a one piece loom without any connections into the bigger loom towards the ecu. Fuses double checked and swapped around. Only thing left would be the can wiring. But that seems to be quite a big thing to check on its own. Im leaning towards ordering a new pump and hoping for the best, but the fact that it started working miraculously yesterday doesnt want me to order one lol. My best bet now would be that the electronics in the pump itself are soaked.

I can look up where the CAN wiring goes to within the cabin at lunchtime (shortly) if it's helpful.  

I'll have a look at the DFM wiring situation for your car whilst I'm at it.  I think if it's intact all the way back to the ECU, you'll see either 5V or 12V on the (unplugged) alternator connector pin that's on the end of the brown/red wire (with ignition on).

Edited 4 October, 20196 yr by Wino

thats very helpfull, also important to know is that my battery light in the dash comes on when put the ignition on. This would indicate that the altenator coms are OK.

 

 

27 minutes ago, Jarnovw said:

I jnplugged all an reconnected,

Did you look at the contacts for corrosion or wetness at all when dong this?

I ask because the easiest route for water entry into the main electronics circuit board is via the connectors, I think.  If water gets inside the loom connectors, it can pass straight into the module.

ye the connectors where dry and i felt inside the large 12v and ground connector on the pump side of it, that seemed to be dry aswell.

Just now, Jarnovw said:

This would indicate that the altenator coms are OK

Partly.

That actually only indicates that the blue exciter wire is intact. Either that one or DFM one can be individually broken, but often both are; which is why some believe that battery light OK = DFM wire OK. It's not true I don't think.

 

how likely would you think its the pump that is the culprit at this point?

Hard to estimate as I've not had it happen to me. Maybe 70:30?

 

Fabias do suffer quite a few failures that are broken/breaking wires rather than the things on the end of them though. 

The loom coming into the engine bay near the engine ECU tends to get a lot of water running down it whenever it rains, due to poor grommet sealing and blocked drain holes in the waterbox. That coupled with heat-cycling and possible abrasion against debris in that area can lead to random wires getting exposed to the elements.

 

It would be good to check the ignition 12V on the black/yellow wire (with ignition on!) as well as the main permanent power feed (which you've done).

Edited 4 October, 20196 yr by Wino

In that case ill probably try and dig up a wiring diagram from somewhere and see if the wires from the can connector are actually still connected to the ECU lol.

mine is a 2002 or 2003, this wiring diagram is from a 2004. By the looks of it its all the same. If i can beep those 2 wires from the can connector all should be ok on the wiring loom side. Hopefully i find some time to do this tomorrow

I'll check for pre-2004 is the same.  Hang on...

Yeah looks like it. 

You may or may not know that the grey block at the top of the diagram you've posted isn't the engine ECU, it's the Onboard supply control unit which is up above the accelerator pedal, and awkward to access. May be easier to check CAN continuity to the engine ECU.  

Bus line A121 (orange/black wires) in your drawing goes to engine ECU pin 20; A122 (orange/brown) goes to ECU pin 21

The diagrams I'm looking at definitely show a 2-way connector pair in "holder on gearbox" for the DFM and exciter wires BTW.

I’m betting with no communication to the pump but it has battery voltage, Earth and ignition feed at the pump then the pump is faulty.