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[Kevin Wood]

This HOWTO has been compiled based on valuable contributions to the forum from NickA, BigAL, Ken T and Welung666 amongst others for which we are grateful.

Later facelift Omegas came with two options regarding intermittent wipers. An optional rain sensor at the top of the windscreen provides variable intermittent wipe automatically. Unfortunately, on cars lacking this option, only a fixed delay intermittent setting was provided.

The manually variable intermittent delay fitted to older Omegas was dropped. The fixed delay is never quite right for the level of rainfall, so it is a worthwhile modification to add variable delay functionality. There are two options, as described:

Retro-fitting a variable delay stalk from an earlier model

This is not too difficult to do. It requires a small modification to the wiring around the stalk and swapping of the intermittent delay timer module.

The first job is to obtain a wiper stalk and timer module from a car with variable intermittent delay. The stalk has an extra thumbwheel in the arm to adjust the delay. This is in fact a variable resistor. On a fixed delay setup, the positive supply is switched via terminal "J" of the stalk via a wire (black with yellow stripe) to the delay module which contains an internal resistor to set the delay. On a variable setup, the variable resistor is inserted into this connection, making the delay variable. The timer module in this instance has a smaller resistor to set the minimum delay, hence the requirement to also swap the timer module to get the correct adjustment range.

To remove the stalk first the steering column cowling must be removed. This is achieved by removing the 3 posidrive screws in the bottom of the cowling and then the 2 countersunk screws in the front of the cowling that are accessible when the steering wheel is turned to the "90 degree" position each side. Unscrew and remove the steering column height adjust lever and remove the upper and lower halves of the cowling.

The stalk can be removed by squeezing the two levers at top and bottom of the switch body and withdrawing it sideways, then withdrawing the electrical connector from the switch body.

[Kevin Wood]

The variable resistor is connected to an additional connector separate from the main plug on the base of the stalk. Normally a variable stalk has an additional 6 pin connector on a flying lead, of which 5 pins on this connector are populated. 3 of these connect the 2 buttons to control the MID (if fitted) and the other pair (black and while stripe, and black and yellow stripe) are the variable resistor for the intermittent wipe. This is what the 6 pin connector looks like (courtesy of Big AL):



Cars without variable intermittent wipe will have a 4 pin connector only for the MID connections. There will be other variations, for example, on models which don't have the MID buttons on the stalk. This is the 4 pin connector:



In order to avoid too much modification of the car's loom, I found that the MID wiring can be swapped easily by removing the plastic lug that holds the pins into the connector, on both the 4 pin plug from the old stalk and the 6 pin plug on the new stalk. The pins can then simply be swapped from the 6 pin plug to the 4 pin plug so they will connect to the existing connector in the car's loom. Note that the MID wires are colour coded brown, red and white on some stalks. On others the red and white are replaced by brown and red and brown and white respectively.

This shows the plastic retaining clip removed. This was achieved by pressing the 2 small yellow tabs with a small screwdriver



..which will allow the small sockets on each wire to slide out, once they have been freed..



To release the sockets from the plastic holder insert a pin of some sort down the hole towards the centre of the plastic connector, this releases the tab locking the socket into the connector allowing you to push them out of the connector using a small screwdriver

[Kevin Wood]

This should leave you with a stalk that will physically connect to the car but with a black and white and a black and yellow wire left over from the stalk.

These wires need to be connected in series with the black and yellow wire from pin J of the connector at the base of the stalk.

Identify pin "J" (NOTE: this may well have a black and white wire in addition to the black and yellow wire present. This is normal. It's a supply to the connector where the rain sensor would be). Note that there is a second black and yellow wire to another connection on the stalk, so be sure that you have correctly identified pin "J" from the legends on the bottom of the stalk.

Cut the black and yellow wire going to pin "J" leaving a couple of inches free. It might be helpful to tease this wire out of the lacing a little further up the wiring loom to liberate a little more free length. I soldered a mating pair of spade connectors to the ends of this wire so the original arrangement can be easily re-instated if required.

Solder another pair of spade (or bullet, etc. whatever's to hand) connectors to the free ends of the spare wires on the stalk. It doesn't matter which way round the variable resistor in the stalk is connected. Each of the wires from the stalk needs to be connected to one end of the black and yellow wire we have just cut.

Once the connection is made, apply some heat shrink sleeving or similar so that it is well insulated. Assemble the stalk but leave the steering column cowling off until it has been tested.

The following picture shows these wires joined by soldering followed by heat shrink sleeving (thanks to NickA):



Swapping the timer module is straightforward. It can be found in the engine bay relay box by the battery. It is a tall yellow module just in front of the two purple (engine management and fuel pump) relays at the back of the box.

Once this has been carried out, switch on the ignition and set the stalk to intermittent wipe. Check that the control allows the delay to be varied between about 3 and 16 seconds.

If a replacement timer from a car with variable intermittent wipe is not available, the following contribution from Ken T will be of interest:

I did the mod replacing the wiper stalk with one with a variable control, however the delays were too great, from 7sec to 15sec between sweeps. After a bit of investigation, I discovered that the minimum time was set by a 3K9 resistor on the wiper relay ( K8, tall yellow, 2nd from the right in the fuse box, with 2 fuses attached to the holder). After some experiments, I found that if you replace the the 3K9 with a 1K it gives a minimum sweep time of about 3secs, eg delay of 1sec, which is a lot more usable.

Its a bit of a fiddle getting into the relay, but not impossible. Don't ram something in too far or you might damaged the relay which is close to the sides.

I wouldn't go much lower than 1K, the controlling IC isa a TY93029A which I have never heard of, but 1K shouldn't cause any harm. I measured the variable pot as going from 600R to about 5K, so should be a safe mod.

[Kevin Wood]

Alternative solution using VW "learning" timer module

I have come across a VW part which implements variable intermittent wipe in quite a neat way.

This wiper delay timer "learns" the wiper interval in the following way:

It starts drizzling, so you flick the wipers once. It keeps drizzling so, when the screen is in need of another wipe, you set it to intermittent. The wiper delay timer sets itself to the time interval between your initial "flick" of the wipers and when you switched it to intermittent, and carries on using that interval thereafter.

So.. No need to swap to a stalk with a variable setting and, the best part, this relay is pin compatible with the non-variable timer module already fitted in Omegas without variable intermittent!

The upgrade simply involves lifting the bonnet, pulling out the old timer module and plugging in the new one.

If anyone wants to do this, you will need the timer module which is VW part number 357 955 531. Also referred to on the net as the "99" relay as it often has a large number 99 printed on the case. This site suggests that there are some equivalent parts but I can't vouch for its' accuracy. http://wiki.seloc.org/a/Wiper_Variable_intermittent

I ordered one from ebay seller stevens_vw_dismantlers and it arrived very fast and in good condition.

So, for those who want to retain the original stalk and avoid modifying the wiring to take the adjustable stalk, this is a nice solution.