BPM wipers hazard liggts

I have a 2000 XKR convertible and when I operate the wipers the hazard lights operate. The time sequence is different from the normal hazard light sequence, it’s from the time sequence for the wipers. If I do one flick of the wipers it turns off hazard lights. I have checked wiper motor, changed wiper relays, have tried to do a pinpoint on BPM, but the manual is incorrect, it says measure the voltage between FC14 pin 80(N) and ground, but there is no wire in 80
The wipers work as they should
Any thoughts anyone

What an interesting problem. When you say the time sequence is different, do you mean the time between between and the duration of the flashes is different to what it is if you activate the hazard with its switch? The reason I ask is because I can’t see a separate timing relay for the hazards so the flash on flash off duty cycle must be generated within the BPM.
If you mean the hazards start as soon as you turn on the wipers and flash at their normal rate while the wipers are running, this fault is easier to understand.
My line of thought is that since the hazard lights are activated by a ground on pin 59 of the BPM the first check is to see if, when you operate the wipers, a ground appears on this pin. I don’t underestimate the difficulty of making this test as the BPM is not an easy module to get at and it has one socking great plug tightly packed with wires. I have spent many happy hours fault finding at this particular plug and socket.
To continue my line of thought, since the wiper functions are all initiated by applying ignition switched volts to the BPM, the cross connection seems to be more likely on the output side as these are grounds from pins 19 & 43 to the wiper motor and fast/slow relays. I wondered if some fraying has occurred in the harness somewhere and one of these wire carrying grounds is shorting to the yellow wire on pin 59. However, if the duty cycle of the hazards is different, a fault within the BPM cannot be ruled out although it would be low down on my most likely list.
I am surprised that you haven’t found a brown wire on pin 80 since this is the logic B+ supply to the module although there is another one on pin 79.
That’s all I’ve got at the moment.

Thank you Eric
The hazard lights start when I operate the wipers
The hazard light sequence is slower than the normal flashing. Also if I use the flick option on the wipers it stops the hazard lights operating and continues a wipe cycle
I think I am viewing the plug correctly, when I take it apart and look at the face of the plug with segment at either end uppermost pin 80 is 2nd from left on top row?
Norman

I am thinking the intermittent wipe, which is first to operate dictates the hazard sequence, which is slower than the normal flashing.
I will try and have a look at the points you point out tomorrow and see if I can solve it.
Can I say a big thank you for your help
Norman

Regarding the plug, I think as you describe looking at the plug, pin 80 is second from the right on the top row and should have a brown wire on it. If I am right, second from the left would be pin 103 which is a no connection.

Selecting intermittent wipe will put a sequence of momentary grounds on pin 43, the time interval between them determined by the delay setting. Since all of the direction indicators have individual outputs from the BPM (although, note the 2000MY electrical guide has the legends in the incorrect orrder in the RH tail unit) if they all light at the same time, whatever initiates this must be on the input side.

What happens if you go to slow and then fast wipe?

I found trying to monitor individual pins on the BPM with the plug connected very difficult.

Thank you Eric,
If you go from slow to fast, from what I can remember the sequence stays the same, but will check today
Very much appreciated
Norman

Eric
I have to apologise as I was looking at the plug the wrong way around, tats why I couldn’t find pin 80, anyway sorted now.
Checked all points you highlighted, did pinpoint test again and found pin 15 has a 30 ohm resistance, when it should be below 5.
The inersia switch is on the same link, but I have checked most of the wiring can’t find any shorting. I am thinking it could be the ignition switch which supplies the ground through pin 15, so just going to check that.
Have you had any problems with ignition switch?
Once again Thank you very much
Norman

Personally I have not had any problems with the ignition switch. Rob Reilly has with his S Type which uses a similar switch.

You might be on to something as the signal ground at that point should be better than 30 ohms. The ignition switch is a bit of a fag to access. If you could apply a temporary local ground to pin 15, not easy, I know, and see if that provides a cure.

That particular ground is quite busy and provides a switched ground for many different circuits and modules. Definitely worth checking.

Thank you Eric, I will try today and let you know, I have taken the switch out and tried some contact cleaner in it through what I call vent slots. I need to check the continuity prior to reinstalling, hopefully it will be a lot less than 30ohms.
speak soon
Norman