Quote:
Originally Posted by Serf27
So the live data of the DME showing 0V does not mean the sensor is getting any power, but that the sensor is not sending any power back, thus DME showing 0V for bank1 post cat sensor? [see below] ... The yellow wire does what? [see below -- my concept -- may be incorrect]
3) You’re saying to backprobe the orange wire to see if I am getting voltage while sensor is connected? [No, I omitted the Pin#, see below for correction.]
Can you see/post the fault strategy ISTA shows? Or is the same as this? [see below]
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Unless I am mistaken in my interpretation of the wiring diagram:
1) the Orange wire Voltage from KL87-Activated fuse will be 12V, but that has NOTHING to do with Sensor "Trim" voltage. Orange heater wire only supplies voltage to the Heating Element, which is activated by the DME completing the ground, ONLY when needed after cold start. That wire is NOT connected to the Sensor Signal circuit in the diagram. Checking Voltage at the Orange wire is ONLY a "Sanity Check", as you have NO Separate code for the Heater Circuit in ANY sensor.
2) The Yellow "Signal" wire from the DME to the Sensor Connector is voltage (unknown if 5V, 12V or what) from DME. As to EXACTLY What the DME is reporting as Pre-cat Sensor Voltage, the only thing that makes sense to me is the RETURN voltage via the Black/Red or Black/Green wires (Bank1 or Bank 2). That is JUST a 2-wire Sensor (if you omit the heater), with voltage in and voltage (as modulated by sensor) OUT.
3) I omitted necessary references in my earlier post regarding WHERE to backprobe or insert Pin. What I SHOULD have said:
I would also measure Voltage (in reference to chassis ground) at X62102/3, Pin #3 of Connector X62102, Black/Red Wire, using a pin or "Backprobe" with Sensor CONNECTED to Chassis Connector. If you are getting voltage in (2) but not in this test, then the Sensor or its wiring (between sensor & connector) has an issue.
4) To "Back-Probe" a connector, with Connection Made, you must properly identify the location of the desired Socket in the Plastic Connector, and then insert a probe attached to Meter into back of connector to make contact with the metal Socket. OR, you can simply stick a pin in the wire, NOT necessarily good practice for O2 Sensor wiring exposed to the elements, and Electrical Tape next to Exhaust manifolds/ Cats, is NOT a good idea.
5) If ISTA can display HOW to Diagnose a particular Fault, WITHOUT being connected to the vehicle that has that fault in Module Fault Memory, I am NOT aware of HOW to do that.
6) I would start with comparing Voltage of the 2 Yellow wires at Sockets #4 of the Two Pre-Cat connectors, X62102 & X62202. ONLY if those are the same do you need to backprobe X62102/3, Black/Red Wire to test Sensor & associated wiring. If there is an issue there, you might consider removing that Sensor from the Exhaust and Inspecting/ Bench-testing for wiring continuity. Always look for burned/ melted wiring that is near Exhaust System.
7) If you have Voltage at X62202/4, but NO voltage at the Yellow wire, X62102/4, then there is a wiring/connector issue between that socket & the DME. Hopefully NOT an issue with the DME itself. If you do NOT have ISTA, feel free to ask for MORE ScreenPrints.
If you find any other omissions, errors or "Mis-conceptions", please advise. This is NOT an area where I have any particular experience, other than trying to interpret wiring diagrams.
George