S4 has a scrolling message on dash, saying ABS off. anyone know how to turn it on again. My google search not helping so far. Any help will be appreciated.

 

Any other related messages? What MY is your S4. When is the warning displayed? Instantly after engine start or after you're rolling already?

 

sorry for taking so long to reply. Car is in storage, went there last weekend only to find dead battery. So there's another mystery top solve. What's draining the battery when you leave the car parked up for a few weeks.
Anyhow, to the matter at hand. just been down with a good battery, and here is the result.
car is 1985 S 4. LHD.
On engine start up we get, Antilock off. with a little bright red diagram of a brake disc with an exclamation mark in center.
Then it scrolls to, Differential Contr Off. little diagram of a diff in middle.
this car was imported from Japan so all my manuals etc are in Japanese so no use to me at all.
Again help to sort this will be much appreciated.
Struan.

 

The first thing to replace would be the ABS-relay with this fault. I'm a little surprised about the Diff. Control message and the MY. The electronic differential (PSD) came later into production and there are no MY 1985 S4. What is your VIN?

 

First off, there's no 85 S4.
Second, the 'diff control' is the PSD. Not sure when it showed up (90?), but its also not an 85.
The 'scrolling message' means the digital dash. Also not an 85.

As was asked, what's the VIN.

More importantly, what's the letter in the 9th position.

VIN will be WP0ZZZ92*S86xxxx.
The letter where I put the '*' designates the year.

To your problems:

Parasitic electrical drains are a common problem. The two easiest ways to track them down are:

Hook an ammeter between the ground strap & body, then start pulling fuses. When the current draw drops, you've found it (or part of it).
Use an IR temp gun to 'shoot' the relays after the car has been shut down for a little while. Anything that's warm is still drawing power.

The ABS warning coming on immediately after start up indicates a 'control' problem. The control unit does a self check on start up. Something is causing that check to fail. Could be a power issue (relay), could be a 'brain box' issue, could be something else. If the light stays off until the car starts to move, and then lights up, it's usually a sensor issue.
The "Diff Control Off" is coming on because the PSD is tied into the ABS system. If the ABS isn't working, neither will the PSD.

 

please post pictures of the engine and the dash.
NOTE when parking the car for more than a week,
disconnect the ground strap

 

hello again. Thanks for the advice to date. I'm guessing from your comments it's either not an 85 or not an S4.
vin from plate on inner front guard/fender WPOZZZ92ZLS841985 pictures as requested. I'm not up to speed on posting these so I hope you the images are ok.

 

It's a 1990 S4.
Put the VIN into the decoding thread on top of they page and Rob will give you more infos about your car.

 

Ok, lovely sunny day, so off to the storage shed for another look. I don't know why I never thought to check the fuses. So, guess what. found a blown fuse, replaced it, and now the dash display appears normal.
A short very slow drive around carpark and the lights all stayed off. Tested the brakes at this low speed, and the front wheels locked each time. Is this normal? Does the ABS only activate above a certain speed? I will see if we can get it out onto roadway and try at a higher, above 20kph speed, and see how that goes.
In the meantime any further advice, as always greatly appreciated.

 

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Best case. The clock.

Worst case, the OE alarm has a sensor open, worst worst case, an aftermarket alarm exists.

Sitting batteries want maintainers.

 

..and..how old are those fuel lines?? Just gauging from the rail crossover line...

 

for storage purposes also have a battery charger to output 6 amps.
NOTE a battery tender is not a charger.

Charge the battery every 3 months for 4 hours at 6 amps.

NOTE if leaving the car to sit more than 2 weeks,
disconnect the ground strap in the hatch and cover it.

To find a drain first step is to remove the passenger parcel tray and the floor mat and the CE panel cover.
go drive the car, park it with the windows down and hatch hood and doors closed.
look into the doors verify the rear edge lamps are out.
open the glove box verify the bulb housing is cold,
if warm then it is staying on.

come back in 5 mins reaching through the open window shoot the CE panel relays with your IR gun see if any are hot,
find the aftermarket fan circuitry and shoot that, if under the hood reach in through the open window and open the hood.
anything thats warm is running.

 

Back to the ABS: I'd say check out the wiring harness at each of the four wheels for wear and breaks, esp the back two. Those grommets tend to fail over the decades, and in the rear it means the wires will fall right on the drive shaft axles. All of the grommets need to be in place. Roger has spare sets that work very well.

 

On a 1990 S4; if your PSD diff is throwing a fail (like in your pic); then you will also more than likely get an ABS fault. Just my two cents, but before you chase the ABS fault, go and get your PSD pump serviced. I also think an abs fault will disable the psd.
If you are mechanically inclined: search this forum for guidance on the PSD. I'm not sure if its in the DIY section, but start there for sure.