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

The distributor pickup coil on the 1989 to 1991 Dodge Ram pickup with the 3.9L V6 can easily be tested. You don't need any expensive diagnostic equipment, just a multimeter will do.

In this engine, the pickup coil pulls double duty. It takes care of both the camshaft position (CMP) and the crankshaft position (CKP) signals. There's no separate CKP sensor bolted to the bell housing like you'd see in the 1992 to 2001 models.

In this tutorial, I'm gonna show you the three quick tests you need to do to figure out if the pickup coil's doing its job or if it's done for.

APPLIES TO: This tutorial applies to the following vehicles:

• 3.9L V6 Dodge Ram 150 Pickup: 1989, 1990, 1991.
• 3.9L V6 Dodge Ram 250 Pickup: 1989, 1990, 1991.

IGNITION SYSTEM WIRING DIAGRAMS:

• Ignition System Circuit Wiring Diagram (1989 3.9L V6 Dodge Ram Pickup).
• Ignition System Circuit Wiring Diagram (1990-1991 3.9L V6 Dodge Ram Pickup).

OTHER CMP SENSOR TESTS:

• How To Test The Camshaft Position Sensor (1992-1995 3.9L V6 Dodge Ram Pickup).
• How To Test The Camshaft Position Sensor (1996-1997 3.9L V6 Dodge Ram Pickup).
• How To Test The Camshaft Position Sensor (1998-2001 5.2L, 5.9L V8 Dodge Ram Pickup).

Symptoms Of A Bad Distributor Pickup Coil

Most of the time —though not always— when the pickup coil starts failing or gives out completely, the FI computer throws one of these trouble codes:

• Code 11: No Crankshaft Reference Signal Detected While Cranking.
• Code 54: No Fuel Sync Signal Detected.

If the pickup coil's bad, here's what you're probably gonna notice:

• Engine cranks but won't start: The starter spins up the engine like normal, but the it just won't start.
• Random stalling: One second the engine's running fine, and the next it cuts out without warning —usually at idle or low speed.
• Check Engine Light (CEL): If Code 11 or 54 pops up, the Check Engine Light kicks on to let you know the FI computer lost the distributor pickup coil signal.
• Rough idle or misfires: A weak or jumpy signal from the pickup coil throws off spark and fuel timing, making the engine idle rough or misfire under load.
• Hard starts (hot or cold): You've got to crank the engine for a while before it starts.
• Sluggish throttle or poor power: A glitchy signal from the pickup coil can make the engine hesitate when you accelerate. Throttle response feels weak or choppy.

What The Distributor Pickup Coil Does

On your 1989–1991 3.9L V6 Dodge Ram pickup, the distributor pickup coil sits inside the distributor and is key to starting and keeping the engine running.

It sends out the CMP/CKP signal the computer needs to manage fuel injection and spark —both during cranking and while the engine's running.

Here's a closer look at what it actually does:

• Generates the Timing Reference Signal:
  • When the engine cranks or runs, the pickup coil creates a digital ON/OFF signal for the computer to read.
  • That signal tells the computer which cylinder's on the compression stroke and tracks engine speed (RPM).
  • If this signal's missing, the computer can't fire injectors or spark plugs. Everything just stops.
• Controls both fuel injection and ignition timing:
  • The FI computer uses this signal as the base for firing both the injectors and the ignition coil.
  • Without it —or if the signal's bad— you get no spark and no fuel delivery, even if the engine cranks.
• Replaces a crankshaft sensor:
  • This V6 doesn't use a separate crankshaft position sensor like newer engines do.
  • The pickup coil handles all of it —engine speed and cylinder position go straight from there to the fuel injection computer (Single Board Engine Controller —SBEC).

Circuit Descriptions Of The Distributor Pickup Coil

Pin	Wire Color	Description
1	Orange (ORG)	Power (8 Volts DC)
2	Black with light blue stripe (BLK/LT BLU)	Sensor Ground
3	Gray (GRY)	Pickup Coil Signal

Where To Buy The Distributor Pickup Coil

The following links will help you comparison shop for the distributor pickup coil. I think you'll save a few bucks:

TEST 1: Testing The Camshaft Position Signal

The distributor pickup coil sends out a pulsing voltage signal while the engine's cranking or running. When the signal's active, you'll get 5 Volts DC. When it's off, it drops down to 0 Volts.

Here's the cool part —you can actually catch that voltage jump between 5 and 0 Volts using a plain ol' multimeter. And that's exactly how we're gonna test it.

If the pickup coil's bad, it'll usually freeze on one voltage —no switching— while the engine's turning.

So in this first test, we're gonna tap into the signal wire from the distributor pickup coil and see if that voltage flips between 5 and 0 Volts like it should.

The wire you're after is the grey (GRY) one. That's the signal wire sending the ON/OFF pulses from the pickup coil to the FI computer.

IMPORTANT: The camshaft position sensor needs to stay plugged into its engine wiring harness connector for this test to work. You'll either need to back probe the wire or use a wire-piercing probe to get a reading from the CMP voltage inside the wire insulation. Here's what one looks like: Wire Piercing Probe.

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

Here's how to run the test:

1. 1

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

2. 2

   Unplug the ignition coil's electrical connector. Don't skip this part —it's a safety precaution that'll keep the engine from starting.
   
   NOTE: Leave the distributor cap right where it is. It keeps the pickup coil locked in position.

3. 3

   Switch your multimeter to read DC Volts.

4. 4

   Touch the red multimeter lead to the grey (GRY) wire coming from the pickup coil connector.
   
   NOTE: Make sure the pickup coil stays plugged into its harness. If you disconnect it, you won't get a reading.

CRANKING ENGINE WITH STARTER MOTOR:

1. 5

   Once the leads are hooked up, have someone crank the engine for a few seconds.

2. 6

   Watch your multimeter —you should see the voltage jump between 5 Volts and 0 Volts DC while the engine's turning over.
   
   NOTE: If you don't see that voltage switching, perform steps 5 and 6 under "CRANKING ENGINE MANUALLY".

CRANKING ENGINE MANUALLY:

1. 5

   Grab a 1/2-inch ratchet and socket and use it on the crankshaft pulley to turn the engine by hand.

2. 6

   As the crankshaft turns, the multimeter should show the voltage flipping between 5 Volts and 0 Volts DC.

Let's go over what the test results actually mean:

CASE 1: You saw the voltage flip between 5 and 0 Volts. That's the result you want to see.

This tells us the pickup coil is working like it should. It's not the reason your 3.9L V6 Dodge Ram pickup won't start.

CASE 2: The voltage stayed frozen —no switching at all between 5 and 0 Volts DC. That usually means the distributor pickup coil is shot.

But before you swap it out, double-check that it's actually getting power and Ground. That's your next step: TEST 2: Making Sure The Distributor Pickup Coil Has 8 Volts.