| Author | Message | ||
     Cliff Biggs Experienced User Username: cliffy Post Number: 128 Registered: 09-2021 |
Trying to troubleshoot O2 sensor wiring and can't find any wiring diagram that shows this unit in the right side of the boot. Can anyone point me to a wiring diagram for this unit? I have looked and looked and find nothing except the work shop manual reference to reset it by pushing the button. 1986 Spirit USA model O2 light came on, reset button and light stayed off for months then light came back on. Changed the O2 sensor with a Bosch unit (new, east job) and can't reset the light to off after the new O2 sensor. I think the system is working correctly as my mileage hasn't dropped down from when the light was off. I guess I can disassemble the unit and see how things are inside but I'd like to check the wiring before I go that far. | ||
| Robert J. Sprauer Frequent User Username: wraithman Post Number: 844 Registered: 11-2017 |
Did you read this section? https://rrtechnical.info/sz/sz80/u.pdf U2-21 | ||
| Cliff Biggs Experienced User Username: cliffy Post Number: 129 Registered: 09-2021 |
Yes I did In figure U2-27 item 18 and 25 show the 12 volt feed TO the mileage counter (obviously looking for a ground) for the O2 sensor bulb (17) I need the wiring below 18 and 25 to see what makes up the inside of the mileage counter. Can't find that anywhere. The counter has at least 4 wires running into/out of it and I want to find where they go also. Still searching every diagram I have yet no answers. | ||
| Cliff Biggs Experienced User Username: cliffy Post Number: 133 Registered: 09-2021 |
To close out this thread- The problem is corrected! Found a VW wiring diagram with the same VDO counter and saw that the switch only grounds the light to illuminate it. Obviously there is a contact inside the box. Decided to disconnect the mileage tripper in the boot and noticed that the O2 light worked properly. Light on at start but dies when O2 sensor gets hot. Reconnected the box with sensor hot and the light was illuminated slightly so the problem is in the box. Opened the box and looked at the innards. Quite a rig of spur gears and worm gears working off of a stepper electric motor, 1940s technology. Seeing that the switch that grounds the O2 light was just barely making contact I saw how the reset must be pushed WAY up inside its hole to completely reset the counter. Once that was done the points were well separated to open the grounding circuit. Lesson learned- to reset the counter take a small screw driver and push the white button WAY up into the reset hole until you feel and hear the switch reset. . | ||
| Patrick Lockyer. Grand Master Username: pat_lockyer Post Number: 2587 Registered: 09-2004 |
Well done most helpful. |
