Intermittent wipers

[Colin Park]

Where can I find instructions for repairing intermittent wiper black box?

[Jonathan Kay]

Which unit do you have? Start here.

Jonathan

[bjw]

There is a Lucas unit (6DA) with the connectors moulded into the case, and the Technisol unit where the connectors are on flying leads.

The Lucas unit uses a custom chip, whereas the Technisol uses a PIC microcontroller, but both use two relays in the same configuration to do the switchng.

Technisol:-

Lucas:-

What is the fault?

Cheers

 

[Colin Park]

Technisol

[Jonathan Kay]

Are you sure that the fault is in the unit rather than the switch, connectors, fuse etc??

Jonathan

[Colin Park]

No wipers - bypassed unit - wipers. 

Recall seeing a post saying it could be the oscillator. 

[Colin Park]

Yes, bypassed unit and have wipers 

[Colin Park]

Yes, bypassed unit and have wipers 

[Jonathan Kay]

Full search of the archives.

Jonathan

[bjw]

The underside of the Technisol case is glued and has to be prised off. You'll probably need to strip off the black outer sleeves to enable the board to be pulled out.

The first thing to do is look for any corrosion, leaking capacitors, suspicious looking joints, broken wires...

As you can from the pictures it's a pretty crudely made device. The 'afterthought' components on the rear aren't a good sign, and on mine the large electrolytic was pressed against the sharp points with no padding to prevent puncturing the insulation...

Cheers

[revilla]

There are a couple of Lucas 6DA units in eBay very cheap at the moment. They are a direct plug and play replacement. I think they're also generally regarded as being a lot more reliable than the Technisol units. I would just replace. Just make sure you get one with the same connector design, i.e. coffin-shaped, there's another type (possibly from a Range Rover?) that had the pins laid out differently (a row of three and a row of two)

[bjw]

Recall seeing a post saying it could be the oscillator.

That might be this one:-

https://www.lotus7.club/forum/techtalk/fixed-caterhams-intermittent-wiper-control-box

- but it's always risky to assume you have the same fault...

Cheers

[Colin Park]

Are you saying that the Lucas 6DA is a direct replacement for the Technisol. I may be wrong but I seem to recall some comment on Techtalk that it needed some wiring mods. 

[revilla]

Provided you get the (more common) type with this connector pin layout ...

... rather than this type ...

... there are no changes needed.

The wiring loom was the same on 6DA and Technisol equipped cars. In fact the loom was identical on cars without the delayed wipe option at all; the two loom connectors are just male and female of the same type and can just be plugged directly together to omit the delayed wipe unit altogether.

[revilla]

Actually having said that, the one issue you might find is that the wiring loom may be a bit short to reach the connectors on the 6DA comfortably if you mount it in the same position as the Technisol, as the Technisol has short flying leads.

When I replaced mine I made a couple of short extension leads using Lucas Rists 5 Way connectors such as these: https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.co.uk%2Fulk%2Fitm%2F142449471930

Just a few cm of wire with male and female plugs on either end (two of them). If you make them the same length as the flying leads on your Technisol then the 6DA with the extensions plugged in is effectively an exact replica of what you have.

If you don't have a suitable crimp tool give me a shout and I'll happily make you up a couple of leads.

PS: The 6DA units seem to come moulded in different colour plastics. I've seen black, orange, green and blue. There doesn't seem to be any significance as far as I can tell. I've used black and orange ones on Caterhams and they both worked fine.

[revilla]

Oh and just make sure you get the (more common) 12V version, you do occasionally see them in 24V flavour. This may or may not have something to do with the colour coding. Pretty sure Lucas part number 33449 is a safe bet but these were used on many British cars and you see them listed with the part numbers used by the different manufacturers.

[bjw]

I don't think the 33449 is the correct version:-

https://www.autoelectricalspares.co.uk/lucas-33449-6da-wiper-delay-control-unit-2584-p.asp

I believe it's the 33404 that is required.

Cheers

 

[revilla]

@bjw - On the evidence you have presented, I stand corrected! Thanks for that. I really shouldn't be posting TechTalk replies when I can't sleep at 5am

[Geoff Brown]

Is the wiper delay control unit an OE fit? Must be an early one? Cars fitted with this control unit back in the early 2000s had a high failure rate. Mine did! So I just removed it & never replaced it.

[anthonym]

My wiper delay works but second speed just stops wipers, is this thread relevant to my year 2000 K?

discovered of course in a torrential downpour on Mont Ventoux last week or so. 

anthony

 

[bjw]

Hi Anthony,

If the delay works then most of the electronics must be ok.

Try bypassing the delay unit as previously described. If the high speed then works ok it's most likely a problem with Relay #2 (see diagram in post#3).  If high speed still doesn't function  then obviously it's switch, wiring, connectors or motor...

There's an old post which talks about a simple mechanical problem with the relays (but the photos are long gone):-

https://www.lotus7.club/forum/techtalk/fixed-caterhams-intermittent-wiper-control-box

"However, unreliable component number 2 and 3 are the relays, which contain a small spring which latches the contact in it's default position - I found on mine the small spring had come off the end of the contact, inside the relay, and it was free to flap about. Easily solved with the components in place."

Cheers