P2100 on 2019 Ram 3500: Electronic Throttle Control Motor Circuit Causes and Fixes

What's Unique About the 2019-2019 Ram 3500

On the 2019 Ram 3500, the function of the throttle body differs between the two main engine options. For the 6.4L Hemi V8, it operates like a traditional gasoline throttle body, directly controlling air intake to manage engine speed. For the 6.7L Cummins diesel, the part is called an 'Intake Throttle Valve,' and its primary role is to assist the Exhaust Gas Recirculation (EGR) system by partially closing to create a vacuum in the intake, which helps draw in exhaust gases for emissions control. Despite this functional difference, a circuit failure in either part will trigger code P2100.

Diagnostic Flowchart

Tap your situation to follow the diagnostic path that matches what you're seeing on this vehicle.

Symptoms You May Notice

• Check Engine Light (Malfunction Indicator Lamp) is on
• "Service Electronic Throttle Control" warning message on the dashboard
• Red 'lightning bolt' symbol (Electronic Throttle Control warning light) illuminated.
• Vehicle enters 'limp home mode' with drastically reduced power and speed
• Hesitation or sluggish acceleration
• Rough or unstable idle
• Engine may stall, especially when coming to a stop

Most Likely Causes

1. Faulty Throttle Body Assembly 🔴 High Probability → Shop Fuel Injection Throttle Body A specific batch of throttle bodies on 6.4L Hemi models were identified as faulty by the manufacturer (see TSB 09-003-20 REV. C). On the 6.7L Cummins, the valve is prone to heavy soot and carbon buildup from the EGR system, which can cause the internal motor to bind and eventually fail.
   How to confirm: For 6.4L Hemi, inspect the throttle body for an 'S1' marking and a Julian date between 2419 and 2549, per TSB 09-003-20 REV. C. For all models, test the motor circuit at the throttle body connector with a multimeter. If wiring is good, the internal motor is the likely fault. A diagnostic video by American Diesel Tech on YouTube shows how to load test the two outer pins on the 6.7L Cummins connector with a test light; if the circuit is good, the valve is bad.
   Typical fix: Replace the entire throttle body (or intake throttle valve on Cummins) assembly. After replacement, a throttle relearn procedure must be performed.
   Est. part cost: $500-$1200
2. Wiring Harness or Connector Issue 🟡 Medium Probability Engine vibration can cause the wiring harness to chafe against nearby components. A known issue on 2019+ GM trucks with similar engine layouts (which can be analogous) points to contact with the ECM/TCM bracket, the driver-side upper control arm, and the shock tower bolt. Wires can also break right at the connector due to stress and heat cycles.
   How to confirm: Visually inspect the wiring harness leading to the throttle body for any signs of damage, chafing, or melting, paying close attention to where it passes the ECM/TCM bracket. Check that the connector is securely seated and free of corrosion. Use a multimeter to perform a continuity test on the wires between the PCM and the throttle body connector.
   Typical fix: Repair the damaged section of the wiring harness using appropriate splices and heat shrink, or replace the connector pigtail. Secure the harness away from any sharp edges with anti-abrasion tape and zip ties.
   Est. part cost: $10-$100
3. Powertrain Control Module (PCM) Failure ⚪ Low Probability → Shop Engine Control Module (ECM)
   How to confirm: This is diagnosed by exclusion. If the throttle body and all related wiring have been tested and confirmed to be in good working order, the PCM's internal driver circuit may be at fault. This requires advanced diagnostic tools and should be the last component suspected.
   Typical fix: Replace and reprogram the Powertrain Control Module. This must be done by a dealer or a specialized shop with the correct programming tools.
   Est. part cost: $800-$1500

Rare But Worth Checking

• Lost Throttle Body Calibration: → Shop Fuel Injection Throttle Body

Diagnosis Steps

1. Verify the P2100 code is present using an OBD-II scanner. Note any other codes present.
2. Check for Technical Service Bulletins (TSBs). For 6.4L Hemi models, follow the inspection procedure in TSB 09-003-20 REV. C to check the throttle body's Julian date and 'S1'/'S2' marking.
3. Perform a thorough visual inspection of the throttle body connector and its wiring harness. Look for loose connections, bent pins, corrosion, or any signs of chafing or heat damage, especially near the ECM/TCM bracket.
4. If the visual inspection passes, disconnect the throttle body connector. Use a multimeter to check for the correct voltage and ground signals at the connector coming from the PCM (refer to a service manual for the specific pinout). For the 6.7L Cummins, the two outer pins should have power with the key on.
5. Check the resistance of the throttle motor circuit through the throttle body itself to see if it's open or out of spec.
6. If wiring and power/ground signals are good, and the TSB applies, the throttle body assembly is the most likely cause of the failure.
7. If the throttle body and wiring are confirmed to be good, the final step is to suspect a fault within the PCM itself.
8. After replacing the throttle body, perform the ETC Relearn procedure as specified by the manufacturer. This is critical for proper operation.

Parts You'll Likely Need

• Intake Throttle Valve (6.7L Cummins) (OEM #68253198AA) — This is the most common failure point for code P2100 on the diesel engine, often due to internal motor failure caused by soot buildup. This part number supersedes 68205987AA, 68210508AA, and 68253197AA.
  Trusted brands: Mopar
  OEM price range: $745-$1170
  Aftermarket price range: $450-$700
• Throttle Body (6.4L Hemi) (OEM #53034251AD) — This is the primary cause of P2100 on the gas engine, with a known manufacturing defect affecting some 2019 models as detailed in TSB 09-003-20 REV. C. This part number supersedes 53034251AB and 53034251AC.
  Trusted brands: Mopar, BBK Performance, SKP
  OEM price range: $235-$400
  Aftermarket price range: $250-$400

Related Codes That Often Appear With This One

• P02E7 (Diesel Intake Air Flow Position Sensor Circuit Performance) - Often seen with P2100 on the 6.7L Cummins.
• P2112 (Throttle Actuator Control System - Stuck Closed) - Can accompany P2100 if the motor fails in the closed position.

Technical Service Bulletins (TSBs) & Recalls

• 09-003-20 REV. C: Involves inspecting the Julian date and an 'S1'/'S2' marking on the throttle body for a known manufacturing defect and replacing it if necessary. Applies to multiple Ram and Jeep models.

Platform-Specific Known Issues

• TSB 09-003-20 REV. C: Ram issued this Technical Service Bulletin for certain 2019-2020 Ram 2500/3500/4500/5500 trucks with the 6.4L Hemi engine (and other FCA vehicles). It addresses a batch of faulty throttle bodies that can cause code P2100. The fix involves inspecting the throttle body for an 'S1' marking and a Julian date between 2419 and 2549. If these conditions are met, the throttle body should be replaced. The bulletin also notes to check for a green dot, which indicates the procedure has already been completed.

Mechanic-Grade Diagnostic Values

• ETC Motor Internal Resistance (Both Engines) — expected: 2.5 to 25 Ohms. Failure: A reading of 0 Ohms (short) or infinite/OL (open).
• ETC Motor Circuit Wiring Continuity (PCM to TB Connector) — expected: Below 5.0 Ohms. Failure: A reading higher than 5.0 Ohms indicates excessive resistance or an open in the harness.
• ETC Motor Circuit Short to Ground Test — expected: Above 100 Ohms (ideally OL/infinite). Failure: A reading below 100 Ohms indicates a short to ground in the circuit.
• 6.7L Cummins Intake Throttle Valve Connector Voltage (Key On) — expected: Pin 1: ~12V (Battery Voltage), Pin 2: 5V (Signal), Pin 4: 5V (Supply), Pin 5: Ground. Failure: Missing voltage or ground on the respective pins points to a wiring or PCM issue, not a faulty valve.

Scan Tool Commands That Help

• wiTECH (OEM) or compatible professional scanner: Actuation Test / Throttle Position Test / ETCS Test — To command the throttle plate to sweep from 0% to 100% with the engine off. This visually confirms if the motor is physically working, stuck, or completely unresponsive, helping to isolate a bad throttle body from a wiring issue.
• wiTECH (OEM) or compatible professional scanner: ETC Relearn / Throttle Follower Test — This is a mandatory step after replacing the throttle body assembly. The PCM must learn the new closed, open, and idle positions of the replacement part for it to function correctly.

Wiring & Ground Locations

• (K447) ETC Positive & (K448) ETC Negative — These are the circuit identifiers for the two wires running between the Powertrain Control Module (PCM) C2 harness connector and the throttle body connector.. These are the specific circuits that must be tested for continuity, shorts to ground, and shorts to each other when diagnosing P2100.
• 6.7L Cummins Throttle Valve Connector Pins — The 5-pin electrical connector on the Intake Throttle Valve.. Pin 1 (12V Positive) and Pin 5 (Motor Ground) are the two wires that power the motor. A quick test with a test light between these two outer pins can confirm if the motor circuit has power and ground; if the light illuminates but the valve doesn't work, the valve itself is faulty.
• Throttle Body Housing Ground — An auxiliary ground wire sometimes added by owners, running from one of the throttle body mounting bolts to a solid chassis or firewall ground point.. While not a factory part, forum discussions for Hemi engines suggest that a poor ground path through the intake manifold can cause erratic throttle behavior. In rare cases of unresolved issues, ensuring the throttle body itself is well-grounded can be a valid diagnostic step.

Real Owner Repair Stories

• American Diesel Tech on YouTube (Ram with 6.7L Cummins Engine (year not specified, but 5th gen body style)) — Check engine light with associated throttle codes (P02E9 shown, but diagnosis applies directly to P2100).
  ❌ Tried (didn't work) The technician immediately suspected the intake throttle valve based on experience.
  ✅ What actually fixed it The technician performed a bidirectional test using a scan tool, commanding the valve to actuate. The valve position on the scanner did not change, indicating a failure. He then confirmed 12V power and ground were present at the outer pins of the connector. With power confirmed to be reaching the valve but the valve not actuating, the intake throttle valve was condemned as faulty and required replacement.

OEM Part Supersession History

• 68205987AA, 68210508AA, 68253197AA, 68067161AA → 68253198AA — Standard part revision and consolidation for the 6.7L Cummins Intake Throttle Valve.

Model Year Variations Within This Range

• 2019: The 2019 model year marked a complete redesign for the Ram Heavy Duty trucks (start of the 5th Generation). As a first-year model, it is more susceptible to unique issues and TSBs, such as the throttle body defect on the 6.4L Hemi outlined in TSB 09-003-20 REV. C.