Hot Rod Forum banner

Oxygen Sensor wiring on 96 Ram

10K views 5 replies 2 participants last post by  LATECH 
#1 ·
Hey folks so we've got a 96 1500 with the 318 at 184k miles and it's been throwing codes for the Downstream (rear) o2 sensor, only two sensors on this truck the Upstream and Downstream. I've got two different codes stating the same thing; failure in the rear O2 heater circuit. It's been hard to start, runs kinda choppy until it's warmed up and been consuming more gas than usual but I would think the rear O2 shouldn't have any affect on that and should only read the exhaust flow after the cat.

I found the PCM wiring diagram and everything adds up except that there are no wires going into the pins for the Upstream sensor A24 and A26 :confused:. A25 however does have the Orange/Black wire which I have verified is the correct color for one of the four wires going into the plug/harness underneath the truck for the Downstream O2.

I haven't followed the wires all the way up because they go into a thicker loom that is running along the top of the trans and is quite difficult to get to. And I was thinking of just running new wires and loom from the PCM down to the sensor to avoid whatever brittle mess i might be getting into with the loom.

Both sensors appear fairly new and the only numbers I've found on the sensors don't bring up anything in Google so I have no idea what brand they are.

So my questions are how should I be testing this heater circuit? Is there a fuse or relay for this that could be bad? And also shouldn't there be a Tan/White wire in pin A24 going from the PCM to the pre-cat sensor?

My mom bought the truck off a friend who got it from a used car dealership about 7 months ago. I'm thinking maybe they jerry rigged it or something.
 
See less See more
#2 ·
Kinda tough to say much without looking at the wiring diagram along with you. I don't have one...so.
But, the ASD relay powers the PCM and the O2 heater circuits. So a short in the heater circuit can affect performance.
Also you are correct in thinking the downstream sensor doesn't affect performance. Many guys think the do, but only the upstream is used for stoich feedback.

What code exactly is it setting? Also code description is important.
O2 sensor problem is too generic to evolve a Diag routine from.
The verbal description of the code will help a lot.
 
#3 ·
A1 K32 YL/GY Ignition Coil Driver #4
A2 F18 LG/BK Fused Ignition Switch Output
A3 K18 RD/BK Ignition Coil Driver #3
A4 K4 BK/LB Sensor Ground
A5 K43 DG/GY Ignition Coil Driver #5
A6 T41 BK/WT P/N Position Switch Sense
A7 K19 8K/GY Ignition Coil Driver #1
A8 K24 GY/BK Crank Position Sensor Signal
A9 K17 DB/WT Ignition Coil Driver #2
A10 K60 YL/BK Idle Air Control #2 Driver
A11 K40 BR/WT Idle Air Control #3 Driver
A15 K21 BK/RD Intake Air Temp. Sensor Signal
A16 K2 TN/BK ECT Sensor Signal
A17 K6 VT/WT 5-Volt Supply
A18 K44 TN/YL Camshaft Position Sensor Signal
A19 K39 GY/RD Idle Air Control #1 Driver
A20 K59 VT/BK Idle Air Control #4 Driver
A22 A14 RD/WT Fused B(+)
A23 K22 OR/DB Throttle Position Sensor Signal
A24 K141 TN/WT Upstream O2 Sensor Signal
A24 K41 BK/DG Upstream O2 Sensor Signal
A25 K341 OR/BK Downstream O2 Sensor Signal
A26 K41 BK/DG Right Upstream O2 Sensor Signal
A26 K241 BK/DG Right Upstream O2 Sensor Signal
A27 K1 DG/RD MAP Sensor Signal
A28 K242 DG/LB Fuel Pressure Sensor Signal
A29 K441 TN/RD Center O2 Sensor Signal
A31 Z12 BK/TN Ground
A32 Z12 BK/TN Ground
B1 K54 VT Trans. Temp. Sensor Signal
B2 K26 VT/TN Injector #7 Driver
B3 K115 TN Injector #9 Driver
B4 K11 WT/DB Injector #1 Driver
B5 K13 YL/WT Injector #3 Driver
B6 K38 GY Injector #5 Driver
B8 K88 VT/WT Governor Pressure Solenoid Control
B10 K20 DG Generator Field Driver
B11 K54 OR/BK TCC Solenoid Control
B12 K58 BR/DB Injector #6 Driver
B13 K28 GY/LB Injector #8 Driver
B14 K116 WT/DB Injector #10 Driver
B15 K12 TN Injector #2 Driver
B16 K14 LB/BR Injector #4 Driver
B21 T60 BR Solenoid Control 3-4 Shift
B22 K221 TN/PK Fuel Temp Sensor Signal
B25 T13 DB/BK Output Shaft Speed Sensor Ground
B27 G7 WT/OR Vehicle Speed Sensor Signal
B28 T14 LG/BK Output Shaft Speed Sensor Signal
B29 T25 LG/WT Governor Pressure Signal
B30 K30 PK Transmission Relay Control
B31 K7 OR 5-Volt Supply
B32 K35 GY/YL EGR Solenoid Control
C1 C13 DB/OR A/C Comp. Clutch Relay Control
C3 K51 DB/YL Auto Shutdown Relay Control
C4 V36 TN/RD S/C Vacuum Solenoid Control
C5 V35 LG/RD S/C Vent Solenoid Control
C6 T18 LG/OR Overdrive Off Lamp Driver
C7 G14 PK/BK Trans Temp. Lamp Driver
C11 V32 YL/RD 12 Volt Supply
C12 A142 DG/OR Auto Shutdown Relay Output
C13 T6 OR/WT Overdrive Off Switch Sense
C15 K118 PK/YL Battery Temp. Sensor Signal
C16 G12 TN/YL Generator Lamp Driver
C17 G3 BK/PK MIL (Check Engine) Lamp Driver
C18 G24 GY/PK Service Reminder Indicator Driver
C19 K31 BR/WT Fuel Pump Relay Control
C20 K52 PK Evaporative Emission Solenoid Control
C22 C20 BR A/C Request Signal
C23 C90 LG A/C Select Signal
C24 V40 WT/PK Brake Switch Sense
C26 K226 DB/WT Low Fuel Sense
C27 D21 PK/DB SCI Transmit
C29 D20 OG SCI Receive
C31 G21 GY/LB Tachometer Signal
C32 V37 RD/LG Speed Control Switch Signal
 

Attachments

#4 ·
I checked again now that it's my weekend and i've got some sleep and both O2 signal wires are going into the correct pins to the ECU/PCM.

I can't find the other trouble code but one of them is P0141, I'd pull it with my cheap OBD2 code reader but I just reset the computer earlier.

According to my Haynes manual:

"O2 sensor heater circuit malfunction (cylinder bank no.1 sensor no 2).
 
#5 ·
So there's three common wires coming out of the two sensors, Black with Blue which seems to be the ground, Black and white and then Green and Orange. I'm assuming the last two are the heater wires?

Can I run a resistor for these to make the ECU think it's working properly?
 
#6 ·
I wouldn't run a resistor ,but you can use a test light on the o2 heater+ and the ground to verify the PCM is powering the circuit.
After connecting start the motor and see if it is turning the light on.
The sensor is probably bad, but the test light will verify the PCM power up.
I have had lots of Bosch sensors that were bad recently.
I have switched to denso. They are more money, but they work.
You can also OHM the heater circuit of the sensor. BUT be absolutely sure you have the correct 2 wires.
I cant tell much from the wire color list you gave. No where does it list the heater circuit ground color for the O2 sensor. I would assume that the black/Bl wires are the grounds. Use an Ohmeter to verify that before you do the test light procedure.
Some carmakers power the heater when the ignition is on, and the ground side is PCM controlled. IIRC on a dodge the ground is always applied and the PCM controls the power side of the heater circuit.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top