P0132 Diagnostic: O2 Sensor 1/1 Tests (1996-2003 5.2L, 5.9L V8 Dodge Ram Pickup)

TEST 3: Check For Voltage On O2 Sensor 1/1 Signal Wire At PCM Connector

In this test, we're gonna check if the signal wire for the upstream oxygen sensor (Bank 1, Sensor 1) is shorted to a voltage source —like 5V or 12V— anywhere between the sensor and the PCM.

To do that, we'll measure for voltage directly at the PCM connector, specifically at pin 24 of the BLACK PCM connector. If the signal wire is shorted to voltage anywhere along its path, we'll detect it here.

• 1996-2001: The wire color at pin 24 will either be tan with white stripe (TAN/WHT) or black with dark green stripe (BLK/DK GRN).
• 2002-2003: The wire color at pin 24 will be black with dark green stripe (BLK/DK GRN).

If you don't have a multimeter or need to upgrade yours? This is the one I use and recommend: Tekpower TP8268 AC/DC Auto/Manual Range Digital Multimeter (at: amazon.com).

IMPORTANT: Do not insert your multimeter probe directly into the PCM pin. This can cause permanent damage. Instead, use the method shown here: How To Safely Probe The PCM Connector -Without Damaging It.

SAFETY CAUTION: If the engine has been running, let it cool down completely before performing this test, to avoid getting burned by a hot exhaust pipe (when disconnecting the O2 sensor).

Alright, let's begin:

1. 1

   Disconnect the negative (-) batter cable from the battery.

2. 2

   Disconnect all 3 PCM connectors from the PCM.

3. 3

   Disconnect oxygen sensor 1/1 from its engine wiring harness connector.

4. 4

   Reconnect the battery negative (-) cable to the battery.

5. 5

   Connect the black multimeter test lead to the battery negative (-) post.

6. 6

   Set your multimeter to DC Volts.

7. 7

   Turn the key to the ON position.

8. 8

   Carefully connect the red multimeter test lead to pin 24 of the BLACK PCM connector using a probing method that will not damage the terminal.
   
   On the 1996-2001 pickups, pin 24 has either a TAN/WHT or BLK/DK GRN wire.
   
   On the 2002-2003 pickups, pin 24 has a BLK/DK GRN wire.

9. 9

   The multimeter should register 0 Volts DC.

10. 10

    Have a helper wiggle the engine wiring harness as you monitor the multimeter.
    
    Your helper should wiggle the oxygen sensor wiring harness along its path —from the sensor itself all the way to the PCM area.

11. 11

    Wiggling the engine wiring harness should have no effect on the 0 voltage reading.
    
    If the wiggling causes the multimeter to register voltage, you've got an intermittent short-to-power problem.

Let's interpret your test result:

CASE 1: Voltage is present at pin 24 (5V or more). This confirms that the O2 sensor signal wire is shorted to power.

It's somehow shorting out to another powered circuit somewhere inside the engine wiring harness. Your next step is to repair this short to power to solve the P0132 DTC issue. See:

• Short To Power Repair Tips (1989-2003 5.2L, 5.9L V8 Dodge Ram Pickup).
• How To Safely Probe The PCM Connector -Without Damaging It (1989-2003 5.2L, 5.9L V8 Dodge Ram Pickup).

CASE 2: No voltage is detected at pin 24. This is the correct and expected result.

If code P0132 code keeps coming back, we've got us a humdinger of a problem. At this point, you've already replaced the O2 sensor and verified that its signal wire is OK —as in no short to power issues.

That leaves us with only one likely possibility: The PCM itself has an internal fault.

Make sure to check out this section before moving forward and replacing it:

• Is The PCM Bad?

Is The PCM Bad?

Yes, it's totally possible that a faulty PCM (Powertrain Control Module) is behind a persistent P0132 trouble code that just won't go away —especially after replacing the O2 sensor.

But based on my years of hands-on experience diagnosing fuel injection and engine management issues, let me be clear:

The PCM should be the last thing you suspect.

Why? Because before pointing fingers at the computer, you need to rule out a long list of other, far more common issues that can cause the same code.

And here's the good news: none of these checks require fancy (and thus expensive) tools —just a basic multimeter and some time.

Here's what you need to check and confirm Before even thinking the PCM is bad:

• O2 sensor voltage check: Confirmed that the scan tool is confirming that the signal from O2 sensor 1/1 is stuck at or above 1.2V —or worse, 5–12V DC.
• Visual inspection of the engine wiring harness: Made sure the wiring from the sensor to the PCM is not chafed, melted, or touching the exhaust system.
• No voltage at PCM Pin 24: Confirmed that pin 24 of the BLACK PCM connector is not showing any voltage (TEST 3).
• No connector pin corrosion or damage: Looked closely at the O2 sensor connector and the PCM connector. No corroded, damaged or misaligned pins were found.
• O2 sensor replacement: The O2 sensor has been replaced.

Only after going through all these steps —and confirming that none of them are causing the high voltage reading— should you seriously consider that the PCM may be bad.

It also doesn't hurt to get a second opinion from a professional automotive technician. When you do, be sure to bring a written list of all the tests you've performed and the results.

No tech will instantly know what's wrong with your truck, but if you walk in with solid diagnostic notes, you'll earn their respect —and get better insight.

If you're ready to take the next step, you can try swapping in an used PCM from a junkyard —but keep this in mind:

• It'll need to be flashed with your pickup's VIN. "Flashing" installs the correct programming for your specific engine, transmission, and options.
• You might get away with a quick test if you install a used PCM of the exact same year, engine, and transmission configuration as your pickup. If the code goes away and the truck runs, you've confirmed your original PCM is bad.

So remember —diagnosing a bad PCM is all about process of elimination. If you've ruled out a short to power in the O2 sensor 1/1 circuit, verified that pin 24 isn't carrying 5V or 12V, and confirmed the sensor is working (or has been replaced), then yes —the PCM becomes the logical suspect.

More 5.2L, 5.9L V8 Dodge Ram Pickup Tutorials

I've written several more tutorials for the V8 Dodge Ram pickups that may be of interest to you that you can find in this index:

• 5.2L, 5.9L V8 Dodge Ram Pickup Index Of Articles.

Here's a sample of the tutorials you'll find in the index:

• How To Test The Fuel Pump (1992-2003 5.2L, 5.9L V8 Dodge Ram Pickup).
• How To Test The MAP Sensor -P0107, P0108 (1997-2003 5.2L, 5.9L V8 Dodge Ram Pickup).
• How To Test Engine Compression (1989-2003 5.2L, 5.9L V8 Dodge Ram Pickup).
• Troubleshooting A Blown Head Gasket (1989-2003 5.2L, 5.9L V8 Dodge Ram Pickup).