2 Attachment(s)
O2 Heater Circuit PCM control
I'm diagnosing an O2 sensor issue on my 92 Cutlass 3800 L67 swap, and have found something I either didn't notice when I initially did the wiring or thought it didn't matter and/or forgot about it. The wiring harness I'm using is from a 98 Lumina LTZ. Its O2 sensor heater circuit is powered by the IGN fuse and grounded to the chassis. The engine and PCM I'm using is from an 04 Impala SS. Its O2 sensor heater circuit is powered by the OXY SEN fuse and grounded to the PCM pin C2-48 Heater Low Control Circuit. I currently have nothing wired to that pin on the PCM, which has triggered the P0036 DTC.
Lumina diagram:
Attachment 16824
Impala diagram:
Attachment 16825
From the Impala FSM:
Quote:
The PCM controls the HO2S 2 heater low control circuit with a low side driver. The HO2S 2 heater diagnostic monitors the circuit status through the HO2S 2 low side driver when the engine is running. If the PCM detects that there is a circuit fault present on the HO2S 2 heater low control circuit, DTC P0036 will set. Conditions for Setting the DTC: The PCM detects that the HO2S 2 heater low control circuit status is incorrect for more than 20 seconds.
It doesn't say for what purpose it might need to "control" the O2 heater circuit. Do I need to rewire my O2 sensor to ground the heater circuit to this PCM pin, or can I just disable P0036 in the tune and forget about it? Interestingly, there is no code P0030 set, which is the same issue for O2 sensor 1. That's pin C2-37, which there is also nothing connected to in my harness.
And a related, but more general question: Does disabling a DTC just prevent the PCM from *telling* you about an error, or does it stop checking for it entirely? Or, say for example that this code P0036 caused the PCM to assume there's a problem with the O2 sensor(s) and so it stays in open loop as a result, would disabling the code still result in the PCM knowing about the problem and staying in open loop?
