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paulhide · Posted: Mon Jun 12, 2006 9:23 am Post subject: HELP!..Have I damaged my 4WD?

Help!... Have I damaged my 4WD on my P4? The 4WD keeps disengaging. Sometimes it engages on startup and sometimes it doesn't. Sometimes when it engages, it then disengages after 10 min or 15 min of driving. When it disengages at startup I can hear the electromagnetic couple receiving power, but then clicks off and the 4WD warning light comes back on. If I take the fuse out of the 4WD relay or take the relay out, no power goes initially to the couple so I assume that that cannot be the faulty area as I can hear power going to the couple. I have changed the rear 4WD ECU to no avail and the brake switches are moving in and out happily. A couple of months ago, after throwing the car around some roundabouts, I heard graunching sounds from the back and found that the 195 alloys had ground their insides on the rear turrets and so I put spacers on them. Could this have damaged the system and if so which part of the system or does it simply sound like a wiring fault? Does anyone out there have any ideas please?
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mt

Im nowhere near an expert on the 4wd system but from what you say it sounds like a random disengagement so i would suspect dodgy wiring first.
Can't see how spacers would make any difference other than apply a tad more force to the susp, but i ran mine on 16" rims with 205 width tyres with no probs.

paulhide · Posted: Mon Jun 12, 2006 2:20 pm Post subject:

I just wondered if I might've strained the system when the back wheels dragged on the rear turrets (did rather throw it round the roundabouts), like putting on the handbrake, which is stated as a no-no. If it is wiring, I'm not sure where to look as power is getting to the couple before it shuts off so I guess I've got to work out why it would shut off? Crying or Very sad

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stedee · Alfa 33 Joined: 02 May 2006 Posts: 364 Location: brighouse

if you find out whats wrong and good luck to you i have got most of the p4 setup in my garage that i will get rid of cheap
yours steve
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paulhide · Posted: Tue Jun 13, 2006 8:50 am Post subject:

Problem is, I'm not sure where to look or how to find out what is wrong Exclamation

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tvatavuk · Posted: Tue Jun 13, 2006 9:03 am Post subject:

Hi Paul,
Spacers couldn't damage electric part of 4x4. It is probably electric contact.

When it disengages mid driving, is it while or soon after braking?
When it disengages on startup, is it just one click or is it clickclickclick.. before 4x4 warning light lights.

Try few times to start with brake pedal pressed.
Hope you have some kind of testing equipment, Ohmmeter/shortcircuit/Voltmeter for few next tests.
Brake switches have to work (electronicly) and be in sync Smile

Check 2 connectors for ECM and toothmesh sensor right behind shelve above ash tray in central console.
Take toothmesh sensor wires and check there is closed circuit, when it fails there is no conntact.
Check those same wires from those connectors from under car at end of gearbox ECM and top of it.
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paulhide · Posted: Tue Jun 13, 2006 9:23 am Post subject:

Thanks tvatavuk, that's given me something to go on. I don't think it shut off when braking, though the last time was when parking up. Ages ago it used to click on and off with startup sometimes, but was okay when drove off, now it is just one click and then the warning light comes on. I will try with brake pedal depressed and check the two connectors. I do have a meter, but am not utterly sure what I'm doing with it Embarassed

so I generally just use a piece of wire with a bulb in the middle. Idea

How do you tell whether the brake pedal sensors are in sync?
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paulhide · Posted: Tue Jun 13, 2006 5:13 pm Post subject:

Not much luck so far. If I hold the brake pedal down the warning light never goes on at all and no power goes to the electromagnetic couple, so I think that's as it should be? There seems to be a two wire connector (couple) and a three wire connector behind the dash. If I disconnect the two wire connector, no power goes to the coil at all, but if I disconnect the three wire one I get the same result as I'm getting ie. power to the coil then switch off and 4WD warning light back on so I'm guessing that it's probably something to with this area of the system. Any ideas what these wires are for and how to test them?
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tvatavuk · Posted: Wed Jun 14, 2006 12:05 pm Post subject:

Pressed brake test on startup passed means 4x4 ECU works, and both switches send expected signal when they brake is enough depresed.

Brake switches are in sync when you hear them click at same time.
Before that you have to test them to see if click makes changes on tester.
One switch should disconnect circuit/current at click, other switch should let it pass (tester bulb on on).

bulb tester is ok when you have power on lines. Does that meter have its own batteries?
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paulhide · Posted: Wed Jun 14, 2006 2:48 pm Post subject:

Thanks for the support tvatavuk, I appreciate it. Yes the meter does have a battery, but I'm not really sure how to use it without damaging something. Going to take off the central console in a minute so I can see everything more easily. Although it has gone off mid driving three times, most commonly the 4WD drives fine as if nothing is wrong like this morning, you park and then when you start again it won't work. Frustrating. Crying or Very sad

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paulhide · Posted: Wed Jun 14, 2006 4:58 pm Post subject:

Hoping and praying I've found the answer. The wiring behind the console is not very clever as there have been all sorts of alterations, but I think it may be as simple as a brown six-pin connector. When I disconnected it the 4WD system didn't work at all (no lights, nothing) and when I cleaned the contacts and put it together again everything started working properly when it hadn't before. I hope this is it - would be nice, although the problem has been intermittant..... Thanks again tvatavuk.
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bobbber · Posted: Wed Jun 14, 2006 5:03 pm Post subject:

P4 at NAD then Paul - or you bringing the white one again?

Bob
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bobbber · Posted: Wed Jun 14, 2006 5:09 pm Post subject:

Tino,

I reckon you must be the world authority on the P4 system Very Happy

Bob

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tvatavuk · Posted: Wed Jun 14, 2006 5:41 pm Post subject:

2 Paul
sorry for not answering for a whole day yesterday. I've been preety occupied, and today is not any better. I'm off tonight to bus trip to Florence Italy, God willing I'll be back at monday.

6 and 4 pin connectors next to it are ones that connect all 4x4 wires from front to back.
If you dont have my DIY 4x4 switch guide I could send you old version of it, there you have all wiring diargams you need to learn most about 4x4 in our P4s.
If you do have it, take a look at it and you'll see that 4 and 6 pin connectors on wiring diagram, along with 2,3 pin connectors for tooth mesh sensor and ECM.

2 Bob I've learned from the Best (Keith Walker aka Admin) and with few other guys here, united we have enough knowladge to open AR service.
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paulhide · Posted: Wed Jun 21, 2006 8:06 pm Post subject:

Bollocks! It wasn't just a connector, there is definitely something wrong as I'm not getting anything at all now. Turn ignition on, can hear power going to couple and then disengages and 4WD warning light immediately comes back on. Crying or Very sad

If I use a meter how do I test the 6 pin and 4 pin connectors (or ECU connector) Question

So far I've managed to work out that pins 4 and 5 (on 6 pin connector) are for brake sensors, which go in and out okay, and that the 4 pin connector has something to do with the speedo. Tino..... Keith..... anyone... Question

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mt · Posted: Thu Jun 22, 2006 5:35 pm Post subject:

NIghtmare

And to make it worse mine cut out a couple of times while sedately driving at the weekend. Hasn't done it this week though :S

tvatavuk · Posted: Fri Jun 23, 2006 8:03 am Post subject:

Paul after all you told me I would "narrow it down to few things"

- oxidated conenction on 4x4 connectors, clean all 4 of them ( other 2 for tooth mesh sensor and emc) and as I stated earlier check that wires form those two still have insulation from gearbox to connector.
- sticking 4x4 brake switches
- toothmesh sensor itself (usual suspect when first 2 are ok)
little black box at back between lower end of gearbox/EMC and gearshift lever mount/support
- emc (usual suspect when first 3 are ok)
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paulhide · Posted: Thu Jul 06, 2006 9:00 am Post subject:

FAULTY TOOTHMESH SENSOR Exclamation

4WD system now working. Thanks greatly to Tino Cool

and to Stedee Cool

for supplying the part. Now the rear wheel bearing is going. Rolling Eyes

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mt · Posted: Fri Jul 07, 2006 9:55 am Post subject:

Great news that you've resolved it, impressive work guys Wink

tvatavuk · Posted: Fri Jul 07, 2006 1:22 pm Post subject:

He has done all hard work by himself Cool

I think it is fair to say this Forum got new P4 electronics expert Wink

Cheers
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Laki · Alfasud Joined: 06 Sep 2004 Posts: 74 Location: Ljubjana

Ok...I got sam problems as paulhide....Yesterday I started to fidlle with brake senson and got a result now that when I give conntact, I can hear clutc and lights turns off for a half a second then goes back on and 4WD doesnt work. So I chechk all the winring on "top" side. I susspect this TOOTHMESH SENSOR might be also a problem here. Thing is I am not sure ehat this is and how does it look like or where to find it. Embarassed

Deas anyone have a picture or something?

tnx
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paulhide · Posted: Fri Aug 11, 2006 9:48 am Post subject:

Okay Laki, the tooth mesh sensor is in a small plastic box located at the back of the gearbox with wires going through the floor beneath the ashtray in the dash. Not too hard to get at, but to actually remove the sensor you would have to remove the back of the gearbox locator/tunnel (4X13mm bolts underneath gearstick and then a further 4X13mm nuts at back of the gearbox) and then the sensor is held by a plate with four inverted hex bolts. However you don't need to remove it to test it. Instead you need to get in at the wiring behind the dash under the ashtray. The tooth mesh sensor wires coming from the sensor fit a three pin plug and are red, white and copper (shielding) if I remember correctly. To check the coil is working simply see if there is a circuit through the red and white wires - use an ohmeter to see what resistance there is on a reasonably sensitive setting. If there is nothing then there is no circuit, which is not good. Good luck.
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Laki · Alfasud Joined: 06 Sep 2004 Posts: 74 Location: Ljubjana

hi...Fixed..Problam was with switch on the brake, it was working half/ yes half no....So I have tryed and found the right wire (it did take me about 3h to find it) , put ground on it and voila.....it works superb...I have orded switch from Italy so I hope to get it ASAP, so I can repair it properly....
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prauguste · Posted: Sun Nov 12, 2006 9:55 pm Post subject: Faulty Tooth Mesh Sensor

Just want to say a big thanks to Paul Hide for diagnosing my Perm 4 4WD fault and replacing the tooth mesh sensor. Credit also goes to the members who contributed to this post which led me to Paul.

Thanks

Dave (Minari) · Posted: Mon Nov 13, 2006 11:00 am Post subject:

Just read all that has gone on here, and felt I had to say how nice it was to see people helping each other this way.
Well done all concerned, well done all concerned with the forum too.
Dave
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