Rear wiper puzzle

cxprestigeauto · Post by **cxprestigeauto** » Fri Jul 18, 2008 11:53 pm

OK guys put your thinking heads on 'cause I am officialy confused over this one

Got replacement rear wiper motor from Artic Steel, top guy.

Fitted it and nothing. Swore lots. Tried old motor on battery and if the blue ended wire was connectred it worked! The other two wires do nothing.

Tried running seperate cable from battery to replacement motor fitted to car and lo and behold it works. Check power to motor from wiring loom to find that there is power to all three wires including the blue connector.

So how come it will work when they supply is direct from the battery yet not work off the loom? The voltage seems OK (14V with the engine running) but not tested the current (yet).

I cannot get the self park to work on either motor, either when fitted or taking power straight off the battery. Is this a known problem?

The only other thing is when you first connect the power back into the unit mounted on tyhe car there is a faint 'fizzing' noise like things are shorting out?

I have not taken the new unit apart. The old one is pretty solid and will rotate but not come apart.

All thoughts gratefully received.

Rob

Way2go · Post by **Way2go** » Sat Jul 19, 2008 2:49 am

You will normally require 3 at least 3 connections to a windscreen wiper motor. That is a permanent +(positive) supply, a permanent -(negative) supply and a switched negative supply. The motor contains a switch on the rotating bit so that when the switched supply is removed the wiper will continue until it reaches the park position. There will also be an additional connection for the fast wipe speed. The intermittent wipe is controlled by an external delay module to the normal switched input.
Necessary to refer to Haynes for wiring connections which can be identified by their colour code.

cxprestigeauto · Post by **cxprestigeauto** » Sun Jul 20, 2008 5:00 pm

That helps a bit but still doesn't explain why the motor works when connected directly to the battery but not on the wiring loom even when the voltage is the same!

I am going to have another go on Monday night and will check the ampage drawn just in case there is insufficient current in the principal feed.

Rob

AndersDK · Post by **AndersDK** » Sun Jul 20, 2008 5:18 pm

My pennies on 3 problems :

1) wiring weakness (VERY common)
2) control switch problem (VERY common)
3) understanding the circit function (VERY common)

- with a twinky eye - but still true

cxprestigeauto · Post by **cxprestigeauto** » Sun Jul 20, 2008 5:32 pm

I will certainly put my hand up to lack on knowledge of the circuit!

I am confused as to why ALL the wires are live ALL the time?

The switch operates the pump for the rear washer bottle OK.

I have already had some poor wires/connections for the rear fog light so am quite happy to belive that there are issues with the wiring! Not really looking forward to pulling the headlining out to check it either.

Rob

AndersDK · Post by **AndersDK** » Sun Jul 20, 2008 7:39 pm

OK -

Seems you are deeper in the mud than first anticipated

Lets navigate in on the problem then.

What type of rear wash/wiper control switch does your BX have :
1) The wiper control stalk is fitted with turn/push controls for rear wipes.
2) The rear wipe is a push-to-operate dash located control switch located at the cluster side
3) as 2) but the control switch stays in to give continous wipe - until a second push releases button again.

Note : when started, the wiper motor will cause a battery potiental on all control wires - in the case of a missing chassis earth to the wiper motor. This chassis earth is one of the wires coming from behind the RHS rear lights cluster. There is a separate earth point there eactly for this purpose.

cxprestigeauto · Post by **cxprestigeauto** » Sun Jul 20, 2008 9:17 pm

The wiper is operated off a push button on the dash. First part of press operates pump on screen wash, button will then stay down and wiper (should) operate (continously?).

I have had the rear light clusters out and cleaned up the earths when trying to sort out the fog light.

The earth cable to the motor is in place and seems OK as I have been using the metal shield around the motor as an earthing point for my multimeter.

Rob

AndersDK · Post by **AndersDK** » Sun Jul 20, 2008 11:09 pm

cxprestigeauto wrote:The wiper is operated off a push button on the dash. First part of press operates pump on screen wash, button will then stay down and wiper (should) operate (continously?).

Option 2) then - important to identify the correct wiring harness schematic.
The rear wiper motor unit harness coding :
1) grey wire is earth connects to one side of motor - and to rest position of built in changeover witch
2) blackcable and sleeve spade connector is live +12V (ignition on) to switched positon of changeover switch
3) clear (or white) sleeve spade connector is the common of the changeover witch
4) blue sleeve is the motor +12V feed side (when operating).
The built in changeover switch = the park switch.

Behind the RHS lamp cluster the codes changes via a 3 pole white connector
pin 1) receives blue sleeve grey wire wire from motor and connects to ribbon cable red mar up dash
pin 2) receives white wire white sleeve from motor and connects to ribbon white mark up dash
pin 3) receives black cable sleeve and connects to ribbn (no mark) up dash
The grey wire is connected to earth point.

At motor the black holds a constant +12V and the grey is earth - not so interesting.
2 cables are interesting, as these canges state during operation of wiper.
This is the white and blue connectors. Disconnect these 2 wires for testing.

With ignition off (important !) :
Check that these 2 wires are shorted out - up dash - by the control switch in its resting off position.
If not so - you have a disrupted control switch or cabling up dash.
Push and hold the control switch. Now you should have an open circuit up dash on these wires.
Release the control switch.
Up motor check that these 2 wires have the motor winding resistance.
If not so you have a burnt out park switch or burnt out motor winding.

Ignition on (wires still disconnected for testing) :
The 2 wires up dash should be at no potiential, related to earth or +12V. They are free by the control switch resting position.
If not so, you have a wiring or control switch problem.
Press and hold the control switch.
The white wire should still be free - no petential.
The blue wire should now carry a solid +12V.
Check with a headlamp bulb to test the wiring amperage capability, the only real test to a live +12V wire

The blb should light up bright and clear.
If not so - you have corroded wiring or a bad control switch.
Now test the black wire too with the bulb. Same logic apples.

cxprestigeauto wrote:I have had the rear light clusters out and cleaned up the earths when trying to sort out the fog light.

The RHS earth ONLY is for the wiper motor. The LHS earth is for both sides rear lights earth.

cxprestigeauto wrote:The earth cable to the motor is in place and seems OK as I have been using the metal shield around the motor as an earthing point for my multimeter.

OK - but are you sure this earth reaches the motor ?
AFAIR there is a short wire from the motor connecting to the mounting bracket plate - where one of the fixing screws holds the earth coming from the RHS rear lamp cluster.
The motor housing itself does not provide earth for the motor windings or the rotor.

cxprestigeauto · Post by **cxprestigeauto** » Sun Jul 20, 2008 11:18 pm

Great stuff, I will need to print this off and work through logically.

I have cleaned by both earths behind the lights but will revisit.

There is a white earthing cable that is attached to the metal mounting plate by one of the bolts that goes through to the plastic boot.

Many thanks.

Rob

DLM · Post by **DLM** » Mon Jul 21, 2008 3:22 pm

Nobody seems to have mentioned it so far, unless I've made my usual misreading of posts, but BX estate rear wiper behaviour is different from the hatch. From memory, it's a toggle, and the estate circuit incorporates a timer. I don't think this makes its way into the Haynes circuit diags.

(1) One ON-press of the toggle button starts off a a few cycles of wipes before stopping, and then an intermittent wipe every few seconds until:

(2) One OFF-press cancels this cycle.

There is cue from the light bulb on the switch as to which state you're in, but I can't remember which way it works! A long press operates the washer, but the effect once released is the same as one "normal" toggle-press.

Could there be a problem somewhere in the delay circuit (missing/defective relay)? I'll look out my sources to see if there's an estate wash/wipe diagram diagram. The way it should behave is detailed in the BX users handbook, which should be online (www.citroenz.com, I think).

Checking it out now online , the user handbook says,

2. Rear wash/wipe

Saloon : Will operate only while switch is held pushed in.
Estate : Three modes available
Light pressure : screen wash.
Latched : screen wipe
Press again to stop.

OK - some possibilities:

Your switch isn't latching (as Anders says, by no means unknown) If to be replaced, you'll need an estate-style latching switch. Should be possible to check out with a continuity test on the appropriate pins of the detached switch. Best detached with the instrument pod released by pushing the switch forwards from behind: there's no need to remove the inner instrument panel.

Some problem in the delay/intermittence part of the circuit, as suggested above.

Wiring break or damage/corrosion, as you suggest in a previous post. Any continuity check needs to be after the delay part of the circuit. Most wiring terminals in a bx behave better after a wire-brush treatment.

[/b]

AndersDK · Post by **AndersDK** » Mon Jul 21, 2008 3:39 pm

You are rigth David.

However the manin difference is, that the wipe timer realy contact set simply takes the place of the standard control switch contact set.

Otherwise the function is exactly he same when "viewed" into the wires from the boot end (which I call "up dash").

But of course you must then be aware that its either realy or control switch at fault, if a function fault is traced "up dash".

cxprestigeauto · Post by **cxprestigeauto** » Tue Jul 22, 2008 5:48 pm

Many thanks for all the advice. I followed Anders instructions last night and found no fault! I took the new motor apart to find all well inside

Now very confused I tried to bypass the boot wiring to see if there was a current drop in the boot loom. Then things got REALLY weird as the Blue connector wiring just seemed to be live at random! Anyway when I had everything back together at one point the wiper started working!!! It wouldn't self park but it did wipe!

I tested it for a few cycles and it continued to wipe so I flung everything back together and changed all the transmission fluid instead (Not a quick task on a 4X4 with a gearbox, oil like brown water, rear diff, not too bad and front transfer box, oil really good!).

I suspect that the wiper fault is with the relay behind the dash but quite honestly if it works then I will let it be!

Took the car for a very quick (and illegal) drive down a nearby dead end lane and she drove really well. The spheres are a bit hard and she really needs a good thrash with some fresh petrol but overall very impressed. All I need to do now is work out what I am going to do with the car! It was supposed to replace the grotty Skoda Felicia estate being run by my brother but he is getting cold feet over fuel consumption and having a 4X4 being bad for his eco credentials

I am quite tempted to run it as my 'winter' classic to keep my CX off the salted roads. I might have to make some alternative parking/storage arrangements though!

Rob

Way2go · Post by **Way2go** » Wed Jul 23, 2008 11:04 am

cxprestigeauto wrote: Now very confused I tried to bypass the boot wiring to see if there was a current drop in the boot loom. Then things got REALLY weird as the Blue connector wiring just seemed to be live at random!

The blue wire will be live at intervals because of the relay contact from the wipe timer BUT it should stay live once the motor starts and it's cam switch takes over. If the motor doesn't start then then this cam doesn't move and your supply is lost until the next timer pulse. The motor may not move either because the motor is faulty or the earth connection is not good enough for the current of the motor or perhaps even the wipe timer relay contacts are "tired & unclean".

cxprestigeauto wrote: Anyway when I had everything back together at one point the wiper started working!!! It wouldn't self park but it did wipe!

If it works but doesn't self park then either the cam switch is faulty in the motor or the motor has been wrongly wired.