I have a three wire sensor and can't find a good wire diagram for them. The connector is a "WeatherPack" 3 pin marked A, B, and C.
It has white wires in A & B, "C" is black.
I know one is 12 volt power to heat it up, the other two go to the ECM.
Anybody have this info?
Its not reading anything but 451 in the datalogging and goes to 447 if unplugged. Car ran for 1/2 hour with no change in the signal. Bought a brand new one and its doing the same exact signal.
Is it fried? Anybody have this info?

 

A & B = heater
C = signal

picture is a courtesy of Vader with colors changed to suit your appliication; make sure the exhaust is grounded well since there's no separate "signal ground" wire in your sensor...

 

Thanks Z,
This is just what I needed.
My 730 setup has a "O2 low" on the ECM that the ground is currently connected to, I'm going to just ground that terminal to the engine and run the O2 ground directly to the motor.
Just so the heater could not ever put the current to the ECM.
Might be overdoing it but I think it is better for the long run.
Thanks again.
JP

 

I rewired the O2 and grounded the E15 terminal from the 730 ECM.
I still am stuck on the 451 value displayed (two dataprograms both show this value).
I checked the E 15 grounded wire from the ECM and it has 1.56 VDC on it when not connected to ground. There is no voltage on the O2 output wire and have over 12V on the heater wire.
Could I have damaged the new one by having the grounding wire run to the E15 ?
Or worse, Did I fry the circuit in the ECM?

 

I'm sorry, here goes the diagram with corrected pinout (previous one must have been for TBI system). Shouldn't be a problem - A6 is the same on 7730; A3, D3 not used, D7 is grounded.
I don't see how could you fry the ECM - E15 should be grounded (checked on few diagrams). With o2 connected voltages should be 0V (E15) and ~.45V (E14), I can't find if 1.5V on disconnected E15 is OK.

 

referencing the diagram below, I had the white from the heater connected to E15.
I don't know what could happen by putting the heater power INTO the ECM there.
The 1.56 I have there now may just be the internal circuit voltage that is trying to get to ground, so I may be ok there.
I think I'll just bite the bullet and buy another O2 sensor (AFS-74 as I have read here they are the best to use).
JP

 

Are all the O2 sensore that are marked "AFS-74" the same? I've got one of those I was thinking about using instead of the Bosch I have, but it wasn't gottne using the part numbers referenced on the boards here.....

Just curious. Have a Great Day!!!


- Vern

 

Curious, why wouldn't you just run constant power (ignition on) to the heater element and a normal ground?

-- Joe

 

That works too (it's how I did mine).....

:lala:

 

https://www.thirdgen.org/techbb2/sho...=sensor+heater here

 

When I was configuring my wiring from scratch, I listed the connection as it shows on the ECM diagram "O2 Lo"
So as I was redrawing my schematic for how my wiring would go. I put the O2 wires as hi and low, then a heater wire that I originally thought would ground through the sensor housing. WRONG
I have since rechecked the original schematic I used as a reference and should not have done it the way I did.
I now have the heater grounded at the dash (due to location of wire) and the E15 terminal grounded as well.
The AFS-74 I saw as described in another post was convincing to me. (I'm not sure where it was, maybe a search would find it)
I personally have no preference, but the points made sounded good, and since it looks like I have to buy another one anyway...
(I hope I don't need a different connector for it )
If I do, I'll settle for the same one I just bought and try not to damage this one.

 

https://www.thirdgen.org/techbb2/sho...ighlight=afs74

RBob has some info listed here on the AFS-74 twards the bottom.
Sounded like he's done some work.