JakeS2

So, my '89 S4 (early '89 actually built circa october-november 1988) has strange central locking issue. Here's the symtomps

- Fuse #1 blown - changed it. Turned driver's door key -> we had a lock-unlock-lock-unlock cycle on the motor and then silent -> fuse #1 blown again. No activity at passanger door so suspect that motor is jammed ?

- Passanger's door works ok from door and is not hard to turn or anything.

- If I lightly touch driver's side door switch the power window relay gives rattling noise. No such behavior at passangers' door?

I'm asking because if there is a known pattern why the central locking on '89 S4/GT starts to have it's own I would like to check that first and then tear all electrics apart and start measuring what is wrong.

edit:yes, I have done searching this and other forums but haven't found symptoms that match my case fully.

westija

Not sure this is it, but it might be:

http://www.kondratyev.com/porsche/te...ctric_80on.htm

"...2. Doors lock and then immediately unlock. The locking system has a mechanical anti lock out feature. When the door is open the latch prevents the door from locking. An attempt to activate the door lock system will cause the locks to recycle and unlock the door. A bad lock motor or linkage can cause the same symptom"

JakeS2

that kinda rings right bells, tnkx @westija.

I belive we have multiple faults here, door swich(es)and worn out motor. let's see when I tear her apart.

JakeS2

It seems we have something more sinister under the hood.

Sometimes (randomly, mostly) we can see something draining 2,2A from the battery when car is idle. Measurement was done:
Battery(+) - harness -> red pin of multimeter -> multimeter -> black pin of multimeter -> Battery (-)

So it looks quite bad. We took all the fuses out and one by-one and monitored drain -> still at 2,2. Then out of the blue suddely it dropped to zero.

So either my S4 is acting as freelancer electicity support person or there is something wrong. Is there other things to check than:

- Alternator's diode bridge : actually we can see charging meter live it's life when car is running. Sometimes it's steady at 13,8 (near 14V) and sometimes it's close to 12V.
- Solenoid / starter shortage : again, can-be issue as sometimes solenoid does not pull starter when turning key, this could also be:
- Ignition switch
- ABS pump : hardly, should hear some noise or something. Btw, can ABS pump be analyzed, i.e. is there relay/fuse for it?

Is there anything else?

So, at least we have table full of items to debug :-D

Mrmerlin

how about the pulling the relays out one by one,
try the blower motor and HVAC relays,
followed by the window relay.
the window relay has a dely built into it so it will stay on for possibly up to a minute

Landseer

Yes.

Inspect with magifying glass if needed each wire on each power distribution plug at the CE panel.
Look for damaged wires.

Remove and completely clean and re-fuse the CE panel. Inspect back for wire melts.

Clean all grounds and door pins. Clean 14 pin connector, remove backs of both halfs and ensure wires are ok, as in no shorts, and that solder joints to plugs are good. 14 pin.

Voltmeter can vary substantially with temp and load.

Could be ignition switch. Can be removed, disassembled and inspected.

Then we can start to isolate and diagnose doorlock issues.

WallyP

On S4 - up, the only way to check for current drainage is to hook up meter, close hatch and doors then wait for several minutes. Only then is the reading significant.

It often takes a careful and methodical process, including taking notes, to find the problem.

JakeS2

Thanks guys, wrote all them up. Right now I am doing measurement to see what's going on in longer term.

When car is running on idle I get only 13,34V on the battery, shouldn't that be closer to 14 (13,8) so I guess the alternator is not pushing what it should. Luckily the bosch alternator bridge is stock stuff at my local wrench shop so I'll get a new one today.

Funny thing. When I close all doors and have hatch open I get 2A drain but if when I close rear hatch it flactuates for a moment between 0,60 and 2A and then continues to be at 2A.

JakeS2

Hah, the flactuation was due to connector being loose on the multimeter. Bottom line : drain is 2.2A - 2.4A even:
- all fuses off
- 14wire connector disconnected under bonnet
- measured immediately after closing boot and in 10min intervals after that. After 30mins it's still at 2.2A. Then I disconnected battery totally.

I'm going to change the regulator for alternator and then investigate the ignition switch. Is there some guide to measure it ?

Landseer

Try first jumpering out the alarm.

JakeS2

@Landseer ; I will. After today's exercise, pls see below:

So, the saga continues. We measured low charging voltage even with brand new battery so I think the regulator and/or alternator has had it. Let's see how it looks like:


As you can see, the seal has given up and due to that there is dirt and mud all over the alternator and it's internals. I'm sending the unit to a local alternator repairshop so they'll clean and overhaul it.

Also the cooling duct had a crack so it was just inviting all the dirt and dust to enter the cooling duct - I'll change it to a new one while I'm at it.

So, what does the drain-o-meter show when alternator was totally disconnected and out from the car ?

2.4A. So back to drawing board, next I'll look at the alarm by-pass.

Mrmerlin

did you follow the instructions in post 5

JakeS2

@MrMerlin, not yet as today was allocated to spend time under the car and taking the alternator out. Later on this week I'll play with relays but I need to build a special tool(tm) to pull those relays...

On note about HVAC ; her cooling flap work at the front bumper, I have not seen many working flaps here in Finland...

I've been trying to read some tech posts but one thing puzzles me - as my differential is true M220 I should not have additional relays scattered around the car, only at the main panel?

dr bob

JakeS2--

-- I chased a 'low charging voltage' problem for a while. It was ultimately solved with a new ground strap at the battery. I had meters attached to various places looking for voltage drop. Replaced the alternator, made a new positive cable from battery to starter. Finally, accepting advice from this group and ignoring what the meter said, bought a new ground strap.

-- Cooling flaps are omitted on GTS and later S4 cars. Flaps are open by default with engine off. Just remove the fuse and they will stay open.

JakeS2

Ok, time to update this a bit.

So we are still at 2,51A drain (with battery fully charged). What has happened so far is

1. Generator is at workshop so they will clean it and overhaul it. That should be ok after that
2. Alarm module is taken out for measurement, no change
3. Door wirings were disconnected to suspect a jammed door motor or something. no change
4. Audio amplifier disconnected, no change
5. Ignition switch connector at the back disconnected, no change
6. 14-wire connector under hood disconnected, no change
7. Pulled all relays (panel, center console and trunk), no change
8. Disconnected red lights from doors, no change (was done before 3.)
9. 1/4" cable near 14-wire connector disconnected, no change
10. Aftermarket (Pioneer) audio system removed, no change
11. Disconnected LH and EZK cables from the boxes, no change

This is one tricky s.o.b. but somehow I dig it.

One thing. Sometimes the starter does not connect the solenoid when starting, this could relate to this problem or not?

Couple questions if you please.
a) For 5. is that sufficient or do I need to tear the whole swich out?
b) AFAIK only LH, EZK, ABS, Starter, Alarm and Alternator are not connected through the fuses/relays in CE panel. Do they have fuses btw?