Power steering readings. Do you seeanything strange?

[dm222]

Its strange yesterday 13.85 today 14.34 at the same conditions

[Breezy_Pete]

Can you do some more logging, to see if the data all moves?

[dm222]

Can you do some more logging, to see if the data all moves?

 

Will do that tonight if the voltage stays at 14.34V

Edited 13 August, 2015 by dm222

[dm222]

Well voltage back to the original status 13,85V

 

I have a huge voltage drop from the alternator...

 

Turned AC on at the maximum, headlights and radio and then tested as this guy says at 09:30 and I read -0,25V, even without moving the steering and rasing the rpm, don't even want to imagine how big the drop is if I do that... Not in all the case tough, only parts of the case show voltage drop, don't understand why because in the same metal piece some locations show drop some doesnt...

Edited 13 August, 2015 by dm222

[Breezy_Pete]

Did you intend to include a link to a youtube video with something relevant at 09:30? 

 

Sounds like you're getting closer to finding your problem.

 

Measure voltage between the ends of the earth lead from battery to chassis, and the one from starter motor to chassis, while engine is running. And from end to end of alternator output cable.

One of those must have a bad connection I think.

[dm222]

Did you intend to include a link to a youtube video with something relevant at 09:30? 

 

Sounds like you're getting closer to finding your problem.

 

Measure voltage between the ends of the earth lead from battery to chassis, and the one from starter motor to chassis, while engine is running. And from end to end of alternator output cable.

One of those must have a bad connection I think.

 

[Breezy_Pete]

The casing of the alternator will have quite a thick layer of aluminium oxide (good insulator), so your 'sometimes there, sometimes not' reading may be to do with whether or not you're pushing through into fresh aluminium. Sharpen the tip of the probe, and see if you get more consistent readings.

[dm222]

Isnt there also an earth led in the power steering?

 

So I can understand the energy flow from postive to negative through the chassis and then connects to battery?

 

So if I do a drop test from the chassis to the  battery (-) and get any voltage the problem is for example in the connection from the chassis to the battery?

Edited 13 August, 2015 by dm222

[Breezy_Pete]

Yes, there's a thick brown earth lead from the two-pin connector on the PAS module, to a bolt just under the headlight unit, which is the return path of current from the pump.

Yes, if you measure any significant voltage from end to end of the wire that connects battery negative to chassis, then that wire is not good.  

I will try to remember to take some measurements on my car tomorrow, for comparison.

[dm222]

Tested again and there is the same voltage drop (0,27V) to the alternator case, to the starter case and to the engine. don't have any idea how to find out wich one is the problem

There is no voltage drop to the chassis

 

Could it be the starter if the starter is not running?

Edited 13 August, 2015 by dm222

[dm222]

Well this video from 7:15 to 9:45 opened my eyes  and answers my previsous question,

 

The problem is when something that is suppose to be inactive is active because there is some bad connection wich drops voltage on that wire and then can't close the solenoid because the solenoid needs 12V to close. 

 

Supposing it's the starter. Because the starter is droping voltage, the voltage avalaible to the pump drops, the consequence is the amps increase to compensate the loss in the voltage (since power(watts) = voltage X amps), more amps means the pump is less efficient, it can lead to overheat (both times my previous pumps failed it was on big trips).

 

Edited 13 August, 2015 by dm222

[dm222]

 For example if I have a voltage in the battery of 13,5V and a 0,27V dropped it means that the real voltage would be 13,8V, wich means the alternator must be OK.

 

As of the cause, actually this is fascinating me, I think I was looking at it the wrong way, something else is causing the problem...

GREEN = OK
RED = SOMETHING IS CONNECTED TO IT THAT IS CAUSING IT.

 

The ones who have reading are the ones that are not OK and not the other way as I was thinking.

 

 

Edit: Actually I've been thinking, I tested at the starter motor case and engine case, wich is wrong I have to test at the yelow points and if there is a differente it's OK, and if there is no difference then the voltage drop is comming from there, am I righ Wino?

 

Edited 14 August, 2015 by dm222

[Breezy_Pete]

I think from the tests you've done, you have found the bad wire/cable. If chassis - battery doesn't show a drop, that means the main earth lead from the battery clamp to chassis is OK.

 

Alternator/engine/starter motor all show a drop and they are all connected to chassis by one big wire, which goes from the upper mounting of the starter motor to a stud/nut on the side of the left chassis leg. I'm thinking that this wire, or corrosion of the connection at one or other end of it, must be your problem, not the alternator.

 

I have photos of both ends of this earth wire somewhere, I'll add them when I can remember where to find them.

 

Only seem to have a picture of the starter motor end. Here

 

I've just taken a photo of the other end of the cable, but I've zoomed in too close so it's not easy to see where on the car you're looking at (It was raining hard and I was in a hurry!).  Just in front of the battery.

 

[dm222]

Didn't had time this morning to almost anything before work, but I've done two tests, but the point 1 is rusted and the point two is painted, but this results say you anything?

 

[Breezy_Pete]

Looks like the connection at the starter motor then (or it could still be the cable). As you see in my photo, it looks corroded/rusted on my girlfriend's Fabia, I guess yours looks similar/worse?

 

Try to get connections with your probes to clean metal on the terminal and the motor body where these two black arrows point, and if you still see 0.27V drop, you just need to take that wire off and clean that connection.  Make 100% sure that you don't attempt to start the engine while that wire is disconnected. The starter motor current would have to find another way back to the battery, and would probably cause damage to other things. Safer to disconnect battery negative first, to completely remove the possibility.

 

If you don't see the 0.27V between those arrowed points, try it from the point you've labelled 1 on your picture, to the terminal in my photo here with the upwards arrow. If you now see the 0.27V, it's the cable itself that is the problem.

 

 

Your starter motor will also work better after fixing this.

[dm222]

Can I remove the ground from the starter without removing the battery? Is it safe?

[Breezy_Pete]

No problem as long as you don't try to start the engine while it is disconnected. Safest if you disconnect battery negative first, then nothing can go wrong.

[dm222]

I will try to find where the problem is but then maybe the best is to leave the car at a specialist because if I fail I could damage the pump again.

[Breezy_Pete]

Once you've decided whether it's just a connection cleaning problem, or a wire replacement, maybe find a friend who is more confident around cars to help you fix it yourself?

The satisfaction you'll get will be much higher, and you'll possibly fix it completely for free if it's just cleaning required (or maybe the price of a beer or two for the friend).

[dm222]

The drop gets bigger as the engine warms, 0,30V and have usually in this test you should raise the rpm to 2000 to find the true value and I didn't that. Because as more enegery is comming the alternator the drop gets bigger

 

This results seem impossible, I've to retest this again!

 

Will focus in the red circle next time!

 

 

Edited 14 August, 2015 by dm222

[Breezy_Pete]

Because of oxide layers you may need to use a little scraping or abrasive paper to be sure that a '0' reading isn't just one probe not making contact.

For the red area test, maybe get an assistant to hold one probe somewhere easy to reach on clean engine metal, while you probe the terminal at the end of the earth wire with the other meter wire.

[Breezy_Pete]

Actually, now that I'm looking at your diagram on a bigger screen, it looks like the '0' that is the reading of just the cable/wire might be an incorrect reading.  If that one said 0.27, every other reading would make sense.

If instead it was the '0' in your red ring that was a false reading, other readings need to change as well before the whole picture makes sense.

[dm222]

Well, tested eveything again...

 

 

After testing the connection between the starter and the cable the drop dropped to 0,07V max and now doesn't go any further... and the steering is a bit harder again (athough this could be because I consumed a lot of battery)

At first by the readings I though it was the cable but then that happen and made me think maybe it's just a bad contact.

What do you think?

Edited 14 August, 2015 by dm222

[Breezy_Pete]

I think it's that cable, but the problem is the connection of the wire inside the crimp terminal, at that starter-motor end of it.  Pushing with your probe and moving the wire around is making it sometimes good, sometimes bad.  Try pulling on the wire and see if it breaks free from the terminal.

Is there a scrapyard anywhere near you where you could get another cable from to try?

[dm222]

Won't try to break the cable because if that happens the car is imobilized.

It's not an easy acess, will check if I can do it myself. I will replace the whole cable, don't know where to find one though.

 

Thank you very much Wino, so happy I found this problem, lets hope this is the problem that caused the two pump burns.

 

Don't understand why the garage that changed the pumps didn't found this! They were testing the car for 2 days both times... It was at Bosch Car Service. Guess that if we want the service well done we have to do it ourselves...

The second time it was under warranty but still ruined my vacations.