How To Troubleshoot OBD-I Code 22 -ECT Sensor Tests (1992-1995 5.2L, 5.9L V8 Dodge Ram Pickup)

By: Abraham Torres-Arredondo
Created: 18 May 2025
Updated: 22 May 2025
Articl Id: 1707

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TEST 6: Checking For Shorts Between ECT Wires Or To Ground

Checking For Shorts Between ECT Wires Or To Ground. How To Troubleshoot OBD-I Code 22 -ECT Sensor Tests (1992, 1993, 1994, 1995 5.2L, 5.9L V8 Dodge Ram Pickup)

In this test, we're going to check for two types of shorts that could be causing the Code 22: ECT Sensor Voltage Too Low or Too High issue:

A short between the two ECT sensor wires.
A short to Ground in either of the wires.

Both of these conditions can occur if the insulation on the wires has been damaged —allowing the bare copper to touch either another wire (creating a short between circuits) or the engine block or chassis (creating a short to Ground).

These kinds of faults often happen deep inside the wiring harness, where visual inspection won't reveal the issue.

We'll first check for continuity between the two wires at the ECT sensor connector. These wires are independent and should not be connected to each other in any way.

Then, we'll check whether either wire is making unwanted contact with the vehicle's metal frame or engine block (Ground). This could happen if the wire's insulation is rubbed through and touching metal somewhere along the engine wiring harness.

IMPORTANT: The PCM connector must remain disconnected during this test to avoid false readings or any other interference from the computer.

OK, these are the test steps:

PART 1: Check If ECT Sensor Wires Are Shorted Together

1
Make sure the battery negative (-) cable is disconnected from its battery post.
2
Double-check the PCM is disconnected from its 60 pin connector.
3
Set your multimeter to continuity or Ohms (Ω) mode.
4
Probe both female terminals of the ECT sensor connector.
5
The multimeter should show no continuity (infinite resistance or no beep).

Any continuity between these two wires indicates a short between them inside the wiring harness.

PART 2: Check If Either ECT Wire Is Shorted to Ground

1
Keep your multimeter in continuity or Ohms (Ω) mode.
2
Place one multimeter lead on one terminal of the ECT sensor connector.
3
Place the other lead on the battery negative cable (still disconnected from the battery post).
4
Repeat for the second wire.
5
There should be no continuity in either test.

If the meter beeps or shows a low resistance value, that wire is shorted to Ground.

Let's interpret your test result:

CASE 1: No continuity between the two wires, and no continuity to Ground. This is the correct result. Both circuits are clean —no shorts. The wiring is in good shape, and the issue lies elsewhere.

If the 5 Volts are still missing, the internal coolant temp circuit inside the PCM may be damaged. See this section: What If The PCM Itself Is Bad?

If the Ground is missing, and continuity is good, you'll need to re-run the test after unplugging all of the components that share the BLK/LT BLU wire to rule out external sensor interference or voltage backfeeding into the Ground circuit. See: Watch Out For Shared Sensor Ground Circuits.

CASE 2: Continuity exists between the two wires. This means the wires are shorted together somewhere inside the harness.

Your next step is to repair this issue. Take a look at these two tutorial:

CASE 3: One or both wires show continuity to Ground. This indicates a short to metal somewhere along the wire's path —likely where the harness rubs against the engine or chassis.

Your next step is to repair this issue. See the following tutorials:

What If The PCM Itself Is Bad?

If you're reading this section, you've done the leg-work. You've gone through every critical test, confirmed your results, and possibly even replaced the ECT sensor with a brand-new one that passed the resistance check.

So, what if everything else checks out, but you're still seeing the ECT sensor triggering the check engine light?

While it's extremely rare, it is possible for the fuel injection computer (PCM) itself to fail —specifically, the internal circuit that handles the ECT sensor signal.

But before you point the finger at the PCM, here's what you MUST have ruled out first:

Confirmed that either 5 Volts and Ground ARE NOT present at the ECT sensor connector (TEST 1).
Verified that the ECT sensor resistance matches the ambient temperature (TEST 2).
Verified that the PCM is receiving the ECT signal with no dropouts or glitches (TEST 3).
Confirmed continuity of both ECT sensor wires from connector to PCM (TEST 4).
Confirmed the wires are not shorted together or shorted to Ground (TEST 5).
Replaced the ECT sensor with a known-good or brand-new one.
Made sure no other sensor sharing the ECT Ground wire is shorted or dragging voltage into the circuit (see: Watch Out For Shared Sensor Ground Circuits).

If —and only if— all of the above have been ruled out with absolute certainty, then yes, the PCM may be the root cause.

The internal ECT circuit inside the PCM can fail in rare cases, and when it does, the PCM may no longer read or respond to the ECT sensor signal correctly. That can lead to:

Incorrect fuel mixture.
High idle.
Hard starts.
Check engine lights with ECT-related DTCs.

At that point, the only definitive way to confirm a PCM fault is to temporarily swap in a known-good PCM and check if the issue disappears. If it does, the original PCM is bad and will need to be replaced.

Bottom line: PCM failure is the last thing you suspect —never the first. Always confirm the basics before replacing an expensive computer.

Watch Out For Shared Sensor Ground Circuits

As a professional automotive tech, one thing I've seen time and time again is a hidden issue that can completely throw off your test results: shared sensor Ground circuits.

The black with light blue stripe (BLK/LT BLU) wire is the Ground wire for the ECT sensor, and it comes directly from the PCM.

But here's the catch: this exact same Ground wire also feeds a bunch of other sensors, including:

Crankshaft Position (CKP) sensor.
Throttle Position Sensor (TPS).
Intake Air Temperature (IAT) sensor.
Vehicle Speed/Distance sensor.
Oxygen (O2) sensors.
Manifold Absolute Pressure (MAP) sensor.
Camshaft Position (CMP) sensor.

The exact list can vary depending on your model year, so it's a good idea to pull up a wiring diagram for your specific vehicle and trace the BLK/LT BLU Ground wire through the circuit. You'll be able to see how many sensors it connects to and where problems might pop up.

Why this matters: If any one of those sensors develops an internal short —especially to voltage— it can kill the Ground path for every other sensor on that circuit.

You may end up chasing an ECT sensor problem that's actually being caused by a completely different sensor dragging voltage into the shared Ground.

I've seen it firsthand —where the Ground wire ended up with voltage on it, confusing the PCM and shutting down multiple sensor signals at once.

PRO TIP: During your voltage or continuity tests on the Ground circuit, if the reading doesn't match the expected result, try disconnecting the other sensors that share the same Ground wire and retest.

This just might be the key to solving the issue by eliminating false readings caused by a faulty sensor elsewhere on the Ground circuit.

If you're still seeing incorrect test results after disconnecting all the sensors on that shared Ground, then you've successfully ruled out the possibility of a shorted sensor backfeeding voltage into the Ground side. The issue lies elsewhere —likely in the wiring or PCM.

Don't let this spook you —this is totally something you can handle. Grab the wiring diagram, trace the shared Ground, and unplug sensors one by one if needed during your diagnostics.

It's not difficult, and it might be the exact step that saves you from replacing a perfectly good PCM.

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:

If this info saved the day, buy me a beer!