transmission

Transmission Speed Sensor - Output

for 1994–2007 Dodge Ram 2500 5.9L I6 Cummins Diesel · 4WD

Difficulty

Easy

Time

1.4 h

Tools

Steps

✓Fact-checked. Built from OLP's spec database, then independently fact-checked line by line with every correction applied. Master-tech sign-off by Chris Hackleman is queued. Cross-check torque values against the factory manual, and stop if anything looks unsafe. How our data is made.

This procedure replaces the output speed sensor on the 47RE/48RE automatic transmission, which monitors output shaft speed for proper shift timing and speedometer operation.

Warnings

⚠The transmission may be hot if recently driven. Allow adequate cooling time before beginning work.

⚠Some transmission fluid will drain when the sensor is removed. Position drain pan accordingly.

ℹ️The output speed sensor is located on the driver side rear of the transmission case, just forward of the rear output housing.

⚠Using ATF other than ATF+4 will cause transmission damage and void warranty. Do not substitute.

Tools required

10mm socket and ratchetEssential

8mm socket and ratchetEssential

Extension setEssential

Torque wrench (10-60 Nm range)Essential

Pick tool or needle-nose pliers

Drain pan (if fluid spillage occurs)Essential

Wire brush

Electrical contact cleaner

Shop towelsEssential

Jack and jack standsEssential

Wheel chocksEssential

As an Amazon Associate and Autel/ANCEL partner, OLP earns from qualifying purchases — how we link. This never changes the specs we publish.

Parts

Output speed sensor × 1 — Mopar 4800879AB or equivalent
Transmission fluid × 1 — ATF+4 only

As an Amazon Associate and Autel/ANCEL partner, OLP earns from qualifying purchases — how we link. This never changes the specs we publish.

Fluids

Mopar ATF+4 — 1 qt

Preparation

Park vehicle on level ground and apply parking brake
Place wheel chocks behind rear wheels
Raise front of vehicle and support securely on jack stands
Allow transmission to cool if vehicle was recently driven
Locate output speed sensor on driver side of transmission, near tailhousing

Procedure

1
Disconnect electrical connector
Locate the output speed sensor electrical connector on the driver side of the transmission. Press the locking tab and pull the connector straight off the sensor. Inspect the connector terminals for corrosion or damage. Clean with electrical contact cleaner if needed.
2
Position drain pan
Place a drain pan directly beneath the output speed sensor. Approximately 0.5-1 quart of transmission fluid will drain when the sensor is removed, depending on fluid level and vehicle position.
3
Remove sensor mounting bolt
Using an 8mm socket, remove the single bolt securing the output speed sensor to the transmission case. Keep the bolt and any hardware for reinstallation.
4
Extract speed sensor
Carefully pull the output speed sensor straight out of the transmission case. Do not twist or pry, as this can damage the case bore. The sensor has an O-ring seal that may cause slight resistance. If stubborn, gently wiggle while pulling straight out. Allow residual fluid to drain into pan.
5
Inspect sensor bore and old sensor
Inspect the sensor bore in the transmission case for metal debris or damage. Use a pick tool to carefully remove the old O-ring if it remained in the bore. Examine the old sensor tone ring for damage or metal debris buildup. Clean the bore opening with a shop towel.
6
Prepare new sensor
Remove the new output speed sensor from packaging. Verify it has a new O-ring installed on the sensor body. Lightly lubricate the O-ring with clean ATF+4 to ease installation and prevent O-ring damage.
7
Install new sensor
Align the new output speed sensor with the bore in the transmission case. Push the sensor straight in until it seats fully against the case. The sensor should sit flush with minimal gap. Do not force or cock the sensor at an angle during installation.
8
Install mounting bolt
Install the sensor mounting bolt and tighten by hand until snug. Using a torque wrench, tighten the bolt to approximately 7-9 ft-lbs (10-12 Nm). Ensure the sensor remains properly seated during tightening.
9
Reconnect electrical connector
Push the electrical connector onto the output speed sensor until the locking tab clicks into place. Gently tug on the connector to verify it is securely latched. Route the wiring away from hot exhaust components and moving parts.
10
Check and add transmission fluid
Start the engine and allow it to idle. Cycle the shifter through all gear positions, then with engine running and transmission in Park (or Neutral per model), and fluid at operating temperature, check the transmission fluid level using the dipstick. Add ATF+4 as needed to bring level to the proper range. Typically 0.5-1 quart will be needed to replace fluid lost during sensor removal.

Reassembly

Lower vehicle from jack stands
Remove wheel chocks
Properly dispose of used transmission fluid at a recycling center

Verification

Start engine and shift through all transmission gears while stationary, verifying smooth engagement
Test drive vehicle and verify speedometer operation is accurate
Verify transmission shifts smoothly through all gears under light and moderate acceleration
Using a scan tool, verify no speed sensor codes are present (P0720, P0722)
Check for fluid leaks around the output speed sensor after test drive
Verify cruise control operates correctly if equipped