Frequency control valve voltage

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BandB
Posts: 16
Joined: Sun Mar 21, 2010 7:53 am
What year is your cabby?: 1988
Do you own a Cabriolet?: Yes

Frequency control valve voltage

Post by BandB »

Bently page 6-11 under "Checking OXS Frequency Valve " sez.."If resistance is OK use an LED test light to check for voltage signal at the connector"

Fig 5-2 shows the procedure using a US 1115 tester connected across the harness connector stating "Voltage from OXS control unit being checked at the harness connector with LED test light"

Does anyone know what this "Voltage from the OXS..." should be? I'm assuming that it can be measured with a DVOM. Am I off base here?


Thanks
"Luvi" is an 88 with the 1.8 litre engine and std trans.
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gull
Posts: 817
Joined: Sun Feb 19, 2006 6:30 pm
What year is your cabby?: 1989
Do you own a Cabriolet?: Yes
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Re: Frequency control valve voltage

Post by gull »

The signal from the control unit is a square wave that alternates between 0 and some value (12V?); it varies the duty cycle to control the valve. Your DVOM won't react fast enough to read the changes in voltage, so you'll read some intermediate voltage. This is also what you're seeing when you use a duty cycle meter or a dwell meter to adjust the mixture.
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