Installing A/F gauge, need to know where O2 signal wire is

[Jon K]

I am installing a Air/Fuel gauge tonight and I need to know which wire on the O2 sensor is the SIGNAL wire (0 - 1v i believe). I need to know where at the DME/ECU it goes because I don't want to tap all the way down at the O2 sensor itself since its exposed to elements and my tap will make it prone to corrosion at the connection, so I want to tap it within the ECU box. Thanks guys!

[Jeanfb]

My bentley shows the YELLOW wire being the signal line at the O2 sensor (4 wire sensor - unit is of the heated type) - That SAME YELLOW wire is then found to be PIN 13 of the DME connector.

The heated type oxygen sensor has its 'heating element' connected between the green and brown(chassis gnd) wires found at the sensor; this heater is controlled by the Oxygen Sensor Relay(located in the e-box) via the Green wire of the o2 sensor... The Yellow wire of the O2 sensor is also Pin 13 of the DME connector provides the DME with the signal being referenced against the Black wire (signal Gnd) provided to the Sensor via Pin 14 of the DME connector - this black wire (Pin 14)provides direct signal gnd via the DME and not chassis gnd - hence supplying a much 'cleaner' reference point to measure from.

I would therefore look to connect my sensory leads between Pin 13 (+signal) and pin 14 (signal gnd) of the DME connector to emulate the Signal found at the sensor itself via The Yellow and Black wires.

**********all above is JMH of course, apply at your own risk ********

[emw525E34]

Jon,

I tap the wires from the connector itself since the connector is rather large with 4 wires. Its located just infront of the firewall on passenger side. Just by the exhaust side near cylinder 6 next to the ECU compartment.
I unscrew the connector, pry out the rubber, then sneak in a coulpe of wires, I took the ground as well to ensure that its common. These small wires can snake off the rubber insultion side. Soldered to the existing pin edges (a bit delicate), then rubber glue insulate the bunch. This way these pair of wires did not obstruct the connector at all.

I had a DVM hooked to these wires for weeks before I homed them into "IN 2" of my Apexi SAFC2. Good luck