Description
1978 VW Bus - EGR Box - Behind the driver's kick panel on some buses (mainly CA models) is the operating time recorder (aka the EGR Box) halfway down the speedometer cable .
It is a mileage based counter that trips a switch at preset mileage intervals.
When the switch closes a light on the dash comes on to remind you to go into the dealership to have your emissions system checked (we all know the EGR system rusts out since it's part of the exhaust and oxygen sensors have a limited life also).
Read the emissions notice in Owner's manual.
When the light comes on, apart from being annoying, you may also fail your emission test if the tech believes it to be the check engine light (CEL).
To reset the EGR light remove the driver's side kick panel and press the white button on the box until you hear a loud click. If you only press the button half way without hearing a click the light will only stay off as long as you press the button. Some boxes have two button (more later).
You can reset the box at any mileage before the switch trips.
Wiring terminals:
- EGR - light in fuel gauge (blue green)
- CAT - light in fuel gauge (blue yellow)
- 61 - blue wire from voltage regulator
- T - EGR ground
- G - CAT ground
Each bulb (1.2w) is powered by the blue wire from the VR. When you turn on the key the light(s) should come on. When the alternator is engages the light will go off, unless the switch has tripped.
If you look at the wiring diagrams you'll find some variation between models:
- 1979: it shows the OXS warning light is activated by the OXS switch. The dash also has an EGR label but it appear to have no bulb behind the lens.
- 1977/78: the EGR warning light is activated by the EGR elapsed mileage switch. No bulb behind the CAT lens.
- 1976: there are two switches in the elapsed mileage odometer, one for CAT and one for EGR. There are also two separate reset switches.
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