Date: Tue, 20 Feb 2001 02:43:48 EST
Reply-To: FrankGRUN@AOL.COM
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Frank Grunthaner <FrankGRUN@AOL.COM>
Subject: Re: Inexpensive O2 Sensors - A Suggestion
Content-Type: text/plain; charset="US-ASCII"
To tell you which colors line up pin-to-pin is sometimes difficult because
the VW wiring harness color code often changes from model year to model year.
Usually, the Bosch color codes are uniform and unvarying.
That said, on the FoMoCo O2 sensor, the white lead pair form the heater
circuit, and the black lead is always the sensor signal return. For your
particular vehicle, the safest thing to do is to measure the resistance
between the leads on your old O2 sensor. This is best done with an ohm meter,
but a light and battery setup will help measure connectivity. In other words,
only two of the wires are internally connected (through the heater). It is
unimportant which one is connected to the 12 Volt terminal on the harness and
which is connected to the ground terminal. This will only work if the heater
on your old O2 sensor has not burned out (rare condition). After determining
the heater combination color code wire your adapter plug accordingly.
Some other comments:
1. In my experience, the grounded shield wire has always been on the VW
harness side of the plug. My experience is with the Golf wire harness, since
I have never had the nefarious pleasure of working on a Waterboxer. In other
words I have had no difficulties with a shield-short-to-sensor problem
sometimes discussed in the archives.
2. The FoMoCo plug and mating connector are water sealed with an O-ring and
anticorrosion grease inside (in response to a water sealing comment made by
another listee).
3. For the color coded record, according to the sometimes correct Bentley
manual:
'86 Vanagon:
O2 sensor signal - Black, to Black Harness
Heater + - Red, to White Harness
Heater - - White, to ? for ground wire on Harness
Shield wire color not given
'87 Vanagon:
O2 sensor signal - ?, to ? Harness
Heater + - ?, to White Harness
Heater - - ?, to Brown for ground wire on Harness
Shield wire color - White
'88 on Vanagon:
O2 sensor signal - ?, to ? Harness
Heater + - ?, to Red/Yellow Harness
Heater - - ?, to Brown for ground wire on Harness
Shield wire color - White
'88-'89 Golf (US):
O2 sensor signal - ?, to Green Harness
Heater + - ?, to Yellow/Black Harness
Heater - - ?, to Brown for ground wire on Harness
Shield wire color - Black
O2 Sensor signal line labeled terminal 1 on the sensor connector
'87-'88 Jetta, '89 Jetta (Ger), '89 Golf (Mex), '91-'92 Jetta (Ger), '90-'92
Jetta/Golf (Mex):
O2 sensor signal - ?, to Green Harness
Heater + - ?, to Red/White Harness
Heater - - ?, to Brown/Black for ground wire on Harness
Shield wire color - Black
O2 Sensor signal line labeled terminal 1 on the sensor connector
Hope this helps,
Frank Grunthaner
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