O2 Heater Relay Behavior ('88 4.0L)

[boxyjeep]

It looks like the O2 sensor heater is powered from terminal 87A on the relay, which should be powered from terminal 30 when terminal 85 is NOT grounded by the ECU and terminal 86 is powered by fuel pump relay. Is this correct? If so, I'm trying to understand what terminal 87's purpose would be (eventually connects to splice "A").

 

I'm in the process of re-wiring my engine harness and everything is going well, except for trying to figure out this relay's behavior.

 

[Ωhm]

8 hours ago, Chargum85 said:

Is this correct?

O2 Heater Relay shown in the schematic is incorrect. Two (2) pins are labeled wrong. Should be as follows:

C228_1(30)(ORN) from Fuel Pump Relay C216_4(87).

C228_5(86)(YEL) from IGN SW C267_I1.

 

8 hours ago, Chargum85 said:

I'm in the process of re-wiring my engine harness and everything is going well, except for trying to figure out this relay's behavior.

As for O2 Heater Relay function when O2 Heater Relay is OFF (deactivated),  O2 Heater element is ON. Now when the ECU see a WOT condition, O2 Heater Relay is turned ON (activated) allowing for full battery voltage to bypass the Fuel Pump Ballast Resistor and supply that voltage directly to the Fuel Pump Motor.

 

Should also mention Fuel Pump Ballast Resistor is bypassed during engine CRANK. Starter Relay C378_BAL.

[boxyjeep]

On 5/24/2020 at 12:34 PM, Ωhm said:

O2 Heater Relay shown in the schematic is incorrect. Two (2) pins are labeled wrong. Should be as follows:

C228_1(30)(ORN) from Fuel Pump Relay C216_4(87).

C228_5(86)(YEL) from IGN SW C267_I1.

 

As for O2 Heater Relay function when O2 Heater Relay is OFF (deactivated),  O2 Heater element is ON. Now when the ECU see a WOT condition, O2 Heater Relay is turned ON (activated) allowing for full battery voltage to bypass the Fuel Pump Ballast Resistor and supply that voltage directly to the Fuel Pump Motor.

 

Should also mention Fuel Pump Ballast Resistor is bypassed during engine CRANK. Starter Relay C378_BAL.

Thanks--this is helpful.