2 questions - Xantia heater blower, and rev counter

[Dommo]

Hi all

I've got a couple of questions that are unrelated to eachother.

My old 2.1TD has been going well with my mate, the only problem he's had so far is his heaters have stopped. It's an early S2 car so I understand it should have the uprated circuit for the ignition switch, also - the heated rear window always works.

He mentioned today that there seems to be a buzz from the dash, I asked if it was the passenger footwell (knowing that's where the fan motor is) and he said he think's so (but it could be somewhere totally different knowing him), he then said it sounded like a sparking kind of sound . This sounds to me like the fan motor has past it's best, but are there any other things it could be?


Second question:

My rev counter has been random for the last few months, if it stops working it'll start working again after anything like half a second to a minute or so, usually after say 5 seconds.

The weird bit however is that SOMETIMES (only sometimes) it is related to the horn, as the following video shows. To me it seems like a potential earthing problem, but the horn doesn't always have this effect so I wasn't certain. Does the rev counter sender even need an earth? Ie, isn't the engine it's earth?

http://s180.photobucket.com/albums/x226 ... 4230c8.mp4

Dom.

[Xaccers]

Get him to check the brown plug that goes to the blower motor, it can get scorched which makes things worse.

The rev counter comes off your TDC/Lift sensor (can't remember if it's either, or just the needle lift sensor), so you might need a new injector with sensor.
I know someone posted what the resisitance of the sensor should be but can't remember for the life of me what it is.

[DickieG]

In addition to Xac's suggestion the buzzing could be from the temperature sensor motor at the left end of the dash, if the motor isn't drawing air across the sensor then temperature regulation goes all over the place.

When your mate says "The heater's have stopped" does he mean there isn't any ouput from the heater fan or the air is coming out of the heater is cold?

[addo]

Does anyone have comment on the waveform/voltage of the two modulation wires into the blower controller?

I am getting a standing voltage (it seems) close to 13V on max setting.

[Dommo]

I don't have the injector sensor, I have the plain Jane early Bosch pump, so where would my sender be?

He means that the fan itself has stopped, the heat works though. Mine has a similar problem to what you describe Dickie, where the o-ring sealing that temp sensor is split allowing heat from the head unit into the sensor, so it blows the correct temperature for about 5-10 minutes, then it constantly blows cold. Putting it on full hot however overrides this sensor it seems.

What is the best way to sort the scortched connector? Some form of conductive grease?

Thanks.

[CitroJim]

Does anyone have comment on the waveform/voltage of the two modulation wires into the blower controller?

I am getting a standing voltage (it seems) close to 13V on max setting.

Adam, try this thread. It explains the voltages you should see...

Dom, if you have the old pump and no ECU then the rev counter works from a sensor right on the back of the engine near the bellhousing. It reads the flywheel but it's not all that accessible; they're known to fail.

If the heater blower brown plug is scorched/making bad contact then repair is nearly impossible as the contacts will have lost their temper through heat. Replacement really is the only answer.

[Xantidote]

Dommo,

My TD has the Bosch pump as yours, and as Jim says, the tacho signal's read off the flywheel. Don't remember it being too difficult getting at it from underneath. It's a small black cylindrical thingy, held in place by one bolt. Mine worked again after I fiddled with it, but not for long, and it's back to it's intermittent operation. Will be interested to hear if you pin down where the problem lies.

Martin