How To Test The Distributor Pickup Coil (1989-1991 3.9L V6 Dodge Ram Pickup)

TEST 2: Making Sure The Distributor Pickup Coil Has 8 Volts

If you've made it to this point, it means the distributor pickup coil didn't show that 5-to-0 Volt switch in TEST 1.

There's a solid chance the sensor isn't sending out its ON/OFF signal because it's not getting power from the fuel injection computer.

So now, we're gonna check if the orange (ORG) wire is supplying 8 Volts DC to the pickup coil.

If that wire's got power, then we'll move on and see if the sensor has a reliable Ground.

Here's how to do it:

1. 1

   Unplug the pickup coil from its connector.

2. 2

   Connect the black lead from your multimeter on the battery's negative (-) terminal.

3. 3

   Set your multimeter to DC Volts.

4. 4

   Turn the key to the ON position —don't crank the engine.

5. 5

   Touch the red lead to the female terminal marked as number 1 (check the connector photo above).
   
   Make sure that terminal connects to the ORG wire.
   
   NOTE: This check is done on the engine wiring harness connector —the one with the round female terminals.

6. 6

   Your meter should show between 7.5 and 8 Volts DC.

Now, here's what your result means:

CASE 1: You're seeing 7.5 to 8 Volts on the ORG wire. That's the reading we want.

Next, we'll check the black with light blue stripe wire to make sure it's got solid Ground: TEST 3: Making Sure The Distributor Pickup Coil Has Ground.

CASE 2: You're NOT seeing 7.5 to 8 Volts on the ORG wire. Without that voltage, the pickup coil won't work.

Most of the time, it means there's an open-circuit in the ORG wire somewhere between the pickup coil and the FI computer.

Finding the exact spot where the wire's broken goes beyond the scope of this guide, but your next step is to trace that wire and fix the open.

TEST 3: Making Sure The Distributor Pickup Coil Has Ground

For the distributor pickup coil to send out its ON/OFF voltage signal, it also needs a solid, reliable Ground from the FI computer.

In this final test, we're gonna check the black with light blue stripe (BLK/LT BLU) wire to make sure it's giving the distributor pickup coil the Ground it needs.

IMPORTANT: The pickup coil gets its Ground directly from the fuel injection computer. Don't connect the BLK/LT BLU wire to 12 Volts —you'll fry the computer. The method I'm about to show you is safe and works great for checking Ground using a multimeter.

Here's what to do:

1. 1

   Unplug the pickup coil from the wiring connector.

2. 2

   Put the red lead of your multimeter on the battery's positive (+) terminal.

3. 3

   Switch your multimeter to DC Volts.

4. 4

   Turn the key to ON —don't crank the engine.

5. 5

   Use the black lead to gently probe female terminal 2 of the connector.
   
   Make sure this terminal connects to the BLK/LT BLU wire.
   
   NOTE: This check is done on the engine wiring harness connector —the one with the round female terminals.

6. 6

   Your multimeter should show between 10 and 12 Volts DC.

Here's how to read those results:

CASE 1: You're seeing 10 to 12 Volts on the meter. That means the sensor's getting good Ground. That part checks out.

If all three of these things happened, it's time to replace the pickup coil:

• No voltage switch between 0 and 5 Volts in TEST 1.
• You got 7.5 to 8 Volts on the ORG wire in TEST 2.
• This test shows the BLK/LT BLU wire has solid Ground.

CASE 2: The meter stayed stuck at 0 —no reading at all. That means the sensor's got no Ground, and it won't work without it.

Most of the time, that's because the BLK/LT BLU wire is broken somewhere between the sensor and the computer.

Finding where the Ground was lost goes beyond the scope of this tutorial —but your next step is to trace that wire and fix whatever's causing the break.

More 3.9L V6 Dodge Ram Pickup Diagnostic Tutorials

I've written quite a few 'how to' diagnostic tutorials for the V6 Dodge Ram pickup and you can find them in this index:

• 3.9L V6 Dodge Ram Pickup Index Of Articles.

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

• Throttle Body Temp Sensor Tests (1989-1991 3.9L V6 Dodge Ram Pickup).
• How To Test The TPS (1989-1990 3.9L V6 Dodge Ram Pickup).
• How To Test The Fuel Pump (1989-1991 3.9L V6 Dodge Ram Pickup).
• How To Test For A Blown Head Gasket (1989-2001 3.9L V6 Dodge Ram Pickup).