Clarification on rain sensor operations please

[goltho]

After my recent debacle with Autoglass chopping the wiring loom for the autodim mirror and rain sensor when removing the old screen, I've had the unplanned opportunity to familiarise myself with the sensor's operation after rewiring everything. (Yes, they have compensated me for my professional services fixing their damage.)

This is the first 75/ZT I've had with an auto rain sensor. I've been playing with it but would like confirmation that it's working correctly please. I'll refer to the stalk positions as:
0 - off
1 - "intermittent/sensor"
2 - normal
3 - fast
... and the intermittent speed twist collar as:
a - fast
b - medium fast
c - slowish
d - dead slow

On ignition/engine start, if the stalk is at 1, the wipers don't operate and are effectively at 0. I understand this is intentional (for good reasons) and requires repositioning during each engine cycle.

On switching to 1 whilst driving, one sweep is made before entering sensor mode. I understand this is also correct. I'm generally happy with how the sensor reacts and works in wet conditions.

On twisting the collar from a to any other setting however, I've been unable to definitively say whether this changes the sensor's behaviour. Should it, and if so, how (e.g. does the collar effectively become a sensitivity setting)?

And does having an auto sensor installed and working correctly mean that there is no manual intermittent operation available?

Thanks.

Dougie.

[Raven Black]

I have the same thing and will be interested to know the answer. Mine also does not seem to let the other intermittent dials work at all.

[macafee2]

I seem to recall being told rain sensor wipers do do-away with one or more features of normal wipers and that is why I did not fit rain sensing.

macafee2

have a look here
https://www.the75andztclub.co.uk/for...highlight=rain

[trikey]

Your diagnosis is correct, the difference in sensing intervals will only be apparent when it rains and the sensor is triggered and the time of the sweep will change according to the position of the wheel.

[goltho]

Originally Posted by trikey

Your diagnosis is correct, the difference in sensing intervals will only be apparent when it rains and the sensor is triggered and the time of the sweep will change according to the position of the wheel.

So you’re saying that position d is the least sensitive setting and will therefore not wipe as often as position a? Effectively behaving similarly to the non-sensor intermittent settings?

Dougie.

[trikey]

Originally Posted by goltho

So you’re saying that position d is the least sensitive setting and will therefore not wipe as often as position a? Effectively behaving similarly to the non-sensor intermittent settings?

Dougie.

Thats correct, the settings are similar to the non sensor settings, the only difference is the frequency that the rain triggers the intermittant wipes, its a bit of a weird set up really.

[xsport]

does the vehicle speed alter the frequency on any of these settings if set from the body control module . is it related to "intelligent wipe " ? just wondered ... or is it an option of choice on T4 that you could pick one or the other ?

[Maxfly]

Originally Posted by xsport

does the vehicle speed alter the frequency on any of these settings if set from the body control module . is it related to "intelligent wipe " ? just wondered ... or is it an option of choice on T4 that you could pick one or the other ?

Speed does affect it, it seems to up sensitivity at 40mph and then again at 50 or 60 I’m sure.
I find since replacing the gel pad that I prefer the way the rain sensing works compared to the 3 year old Ford Ranger I drive for work. Having to reset the wipers is definitely useful and is something the Ford doesn’t do, been caught a couple of times on frosty mornings on that one.

[goltho]

So being an ideal day for studying my rejuvenated auto rain sensor (i.e. blowing a complete storm..), I paid close attention to what difference the various settings made to wiping sensitivity, but also in relation to the rear wiper. It proved most interesting. All references below relate to the stalk being at position 1. The letters relate to the table shown in my first post above.

Front wipers
• positions a-c demonstrated very little sensitivity differences to each other at 50+mph, but did demonstrate increasing sensitivity as the speed reduced (so acted similarly to the intermittent settings on cars without the auto sensor inasmuch as the delays between wipes increased)

• position d however demonstrated a little more sensitivity at 50+mph; there was almost always a (maximum) 1 second delay apart from torrential rain when the wipers operated continuously, as with a-c)

Rear wiper
I decided to experiment with this and was surprised with the results. The rear-wipe collar was turned on and the stalk was again set at position 1.

• position a: one wipe every 5 secconds
• position b: one wipe every 7 seconds
• position c: one wipe every 11 seconds
• position d: one wipe every 15 seconds (also default for stalk positions 2/3)

The rear wiper delays were affected neither by speed nor water conditions, just the a-d position of the stalk.

I've never seen any reference to this anywhere nor indeed has anyone mentioned it above so my scientific conclusion based on about 10 consecutive tests during a boring wet & windy Sunday afternoon drive, is either that I've discovered a hitherto-unknown Easter Egg placed by a bored Rover tech, or I perhaps need to download the full user manual and trog through it.

Either way, this groundbreaking discovery is placed in the public domain with no claim of ownership. I'm happy to be able to manually control the rear wipe delay whilst the front enjoys an auto response to rain conditions.

Dougie.

[chicochapman]

Here is the Gospel according to St. Rave -



"When the rain sensor is fitted, normal speed dependant and period adjustment intermittent operation is disabled and
the rain sensor assumes full control of the intermittent wiper function."


Couldn't find anything about the rear wiper though.