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Karlos TDCi

Original Poster:

896 posts

74 months

[news] 
Tuesday 2nd October 2012 quote quote all
I'm trying to diagnose and fix a problem with the heater on my wife's '97 Fiesta. I know there is a well-documented issue with the heater control valve (HCV), which electronically controls how much coolant flows through the heater matrix.

The HCV has been changed approx. 6 months ago, but the problem has returned. I have found a guide on the web on how to test the control panel for the HCV, which sends out a pulsed signal to the HCV. It mentions using a Test Lamp to check for a pulsed signal, "To check this you need to connect a test light to the live side of the battery and the other side to the black / green wire, then turn you temperature half way between min / max you should see the light be either on all the time or it will pulse on and off every minute or so"

What I want to know is, can I use a multimeter instead, as I don't have a test lamp? If so, what would be the best way to wire it up?

Spitfire2

1,370 posts

71 months

[news] 
Tuesday 2nd October 2012 quote quote all
Just use the multimeter as a 12 v DC volt Meter.

Zero = off and 12v ish = on.

Mikey G

4,097 posts

125 months

[news] 
Wednesday 3rd October 2012 quote quote all
Spitfire2 said:
Just use the multimeter as a 12 v DC volt Meter.

Zero = off and 12v ish = on.
That would depend on how fast the multimeter reacts and how fast the pulse is.
Sometimes to see the pulse its best to use the basics and the bulb trick would be a better solution.

//j17

2,037 posts

108 months

[news] 
Friday 5th October 2012 quote quote all
A test lamp's simple and cheap-enough to knock up.

Either:
- 2 of these (£2.58) - http://www.maplin.co.uk/insulated-crocodile-clips-...
- 1 of these (£0.84) - http://www.maplin.co.uk/round-mes-type-e10-1977
- 1 of these (£1.33) - http://www.maplin.co.uk/mes-e10-batten-holder-1941
and wire to suit.
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