P2100 on 2019 Ram 1500: Electronic Throttle Control Motor Circuit Causes and Fixes

What's Unique About the 2019-2019 Ram 1500

For the 2019 Ram 1500, this code is directly addressed by a manufacturer's Technical Service Bulletin (TSB #09-003-20 REV. C). This TSB acknowledges a batch of faulty throttle bodies installed at the factory on several 2019-2020 FCA vehicles, including the Ram 1500. The bulletin provides a specific procedure for technicians to identify the defective parts by a Julian date code stamped on the throttle body housing. This known issue makes a faulty throttle body the most probable cause, far more likely than on other vehicles where wiring or PCM issues might be more common.

Diagnostic Flowchart

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

Generation note: The 2019 model year included two versions of the Ram 1500: the all-new 5th Generation ('DT') and the previous generation sold as the 'Ram 1500 Classic' ('DS'). The TSB and related issues with the electronic throttle control can affect both generations, as well as other FCA vehicles from the same period. It is important to get the correct part for your specific truck and engine (3.6L V6 or 5.7L V8), as they differ.

Symptoms You May Notice

• Check Engine Light is on
• Electronic Throttle Control (ETC) warning light (a red lightning bolt symbol) is illuminated
• Vehicle enters "limp home mode" with drastically reduced engine power and acceleration
• Engine is limited to idle speed and will not rev when pressing the gas pedal
• Engine may stall or have a rough, erratic idle
• Hesitation or no response when pressing the accelerator pedal
• In some cases, a crank-but-no-start condition

Most Likely Causes

1. Faulty Throttle Body Assembly 🔴 High Probability A specific batch of throttle bodies installed on 2019-2020 models are known to be defective, as documented in TSB 09-003-20 REV. C. The internal motor circuit fails, causing the 'open circuit' condition. This is the most common reason for P2100 on this truck.
   How to confirm: Check the Julian date on the throttle body as per the TSB. If the date falls between 2419 and 2549, and it has an 'S1' marking without a green dot, it is the faulty part. Otherwise, diagnosis involves confirming power and ground at the throttle body connector; if signals are present but the motor doesn't work (resistance should be between 2.5 and 25 ohms), the throttle body is bad.
   Typical fix: Replace the entire throttle body assembly and the gasket. 🎬 Watch: Step-by-step throttle body replacement for 2019-2025 5.7L Ram trucks. After replacement, an 'ETC Relearn' procedure must be performed using a scan tool. 🎬 Watch: How to clean and reset your Hemi throttle body.
   Est. part cost: $150-$350
2. Wiring or Connector Issue 🟡 Medium Probability Wiring harnesses in the engine bay are subject to heat, vibration, and potential chafing, which can lead to broken wires or loose connections over time.
   How to confirm: Visually inspect the wiring harness leading to the throttle body for any signs of damage, chafing, or corrosion. Unplug the connector (it has a red locking tab) and check for bent, pushed-out, or corroded pins. Use a multimeter to check for continuity and correct voltage on the (K447) ETC Positive and (K448) ETC Negative circuits between the PCM and the throttle body connector.
   Typical fix: Repair the damaged section of wiring or replace the connector pigtail. The 6-wire connector pigtail is available as a separate part.
   Est. part cost: $20-$60
3. Weak or Failing Battery ⚪ Low Probability
   How to confirm: Modern vehicles are highly sensitive to system voltage. A battery that can't maintain voltage under load (dropping below 11V) can cause numerous electronic glitches, including ETC faults. If the truck starts when jumped but won't restart on its own, the battery is a prime suspect. Test the battery with a load tester to confirm its health.
   Typical fix: Replace the vehicle's battery.
   Est. part cost: $150-$250

Rare But Worth Checking

• Powertrain Control Module (PCM) Failure: This is very rare. Before suspecting the PCM, all other possibilities, especially the throttle body and wiring, must be exhaustively ruled out. A PCM failure would likely be accompanied by other trouble codes and more widespread issues.

Diagnosis Steps

1. Scan the vehicle for all stored trouble codes. Note any other codes that appear with P2100, such as P2110 or P2101.
2. Check for the Electronic Throttle Control (red lightning bolt) warning light on the dashboard.
3. Check battery health. Ensure the battery passes a load test, as low voltage can cause ETC errors.
4. Locate the throttle body on the engine. Inspect the wiring harness and 6-pin connector for any visible damage, looseness, or corrosion.
5. Inspect the throttle body for the 'S1' or 'S2' marking and the four-digit Julian date code as described in TSB 09-003-20 REV. C. If it's a known faulty unit (S1 marking, date between 2419-2549, no green dot), replacement is the confirmed fix.
6. If the TSB doesn't apply, test the circuit. Disconnect the connector. With the key on, check for correct voltage and ground signals at the connector pins leading from the PCM.
7. If power and ground are present, measure the resistance between the two motor pins on the throttle body itself. It should be between 2.5 and 25 ohms. If it's an open circuit (infinite resistance), the throttle body motor has failed.
8. If power or ground is missing, the problem is in the wiring between the PCM and the throttle body, or a faulty PCM (which is rare).
9. After replacing the throttle body, perform the 'ETC Relearn' procedure with a capable scan tool to calibrate the new part.

Parts You'll Likely Need

• Throttle Body Assembly (OEM #53034251AD (for 5.7L Hemi, supersedes 53034251AC, 53034251AB); 5184349AF (for 3.6L Pentastar, supersedes 5184349AC/AB/AD/AE)) — This is the most common failure point for code P2100 on this specific vehicle, confirmed by a Technical Service Bulletin. The entire assembly is replaced as the motor is integrated.
  Trusted brands: Mopar, Hitachi, Bosch, Dorman
  OEM price range: $250-$400
  Aftermarket price range: $150-$250
• Throttle Body Gasket — A new gasket should always be used when replacing the throttle body to prevent vacuum leaks. It is often included with a new throttle body assembly.
  Trusted brands: Mopar, Fel-Pro, Mahle
  OEM price range: $10-$20
  Aftermarket price range: $5-$15

Related Codes That Often Appear With This One

• P2101 — This code indicates a performance issue with the throttle actuator ('Throttle Actuator 'A' Control Motor Circuit Range/Performance'), which can be triggered by the same internal throttle body failures that cause P2100.
• P2110 — This code means 'Throttle Actuator Control System - Forced Limited RPM.' It is a direct result of the fault detected by P2100, where the PCM intentionally limits engine speed as a safety measure.
• P2111 — Indicates 'Throttle Actuator Control System - Stuck Open.' This can be logged alongside P2100 if the internal motor failure prevents the throttle plate from returning to its default position.

Technical Service Bulletins (TSBs) & Recalls

• 09-003-20 REV. C: Addresses MIL illumination with DTC P2100 and limp mode, instructing technicians to inspect the throttle body's Julian date (between 2419-2549) and 'S1' marking. If found and no green dot is present, the throttle body must be replaced.

Platform-Specific Known Issues

• A Technical Service Bulletin (TSB 09-003-20 REV. C) was issued for 2019-2020 Ram trucks for this exact code. It identifies a batch of throttle bodies manufactured between Julian dates 2419 and 2549 that are prone to failure and require replacement.
• Owners on forums like 5thGenRams.com frequently discuss the red lightning bolt and limp mode, with the dealer-installed TSB-related throttle body replacement being the ultimate fix in most cases for the 2019-2020 model years.

Mechanic-Grade Diagnostic Values

• Resistance of ETC Motor — expected: Between 2.5 and 25.0 Ohms. Failure: An open circuit (infinite resistance) or a reading outside the specified range indicates a failed throttle body motor.
• Continuity of (K447) ETC Positive and (K448) ETC Negative circuits — expected: Below 5.0 Ohms. Failure: Resistance above 5.0 Ohms indicates an open or high-resistance in the wiring between the PCM and the throttle body.
• Voltage check for shorts on ETC motor circuits — expected: 0 Volts. Failure: Any voltage present on the (K447) ETC Positive or (K448) ETC Negative circuits (with throttle body and PCM disconnected) indicates a short to voltage in the harness.
• Resistance check for shorts to ground on ETC motor circuits — expected: Above 100 Ohms. Failure: Resistance below 100 Ohms indicates a short to ground in the wiring harness.

Scan Tool Commands That Help

• wiTECH (OEM Scan Tool) or equivalent professional scanner: ETC Relearn / Learn ETC — This function must be performed after replacing the throttle body assembly to allow the PCM to learn the new part's electrical parameters and throttle plate position range.
• wiTECH (OEM Scan Tool) or equivalent professional scanner: Throttle Follower Test — This is a bidirectional test used during diagnosis to command the throttle actuator motor to open and close, verifying its mechanical and electrical operation without the engine running.
• Manual Procedure (No Scan Tool): Accelerator Pedal Relearn Procedure — As a basic reset, this can sometimes resolve minor glitches. Turn the ignition to ON (engine off), wait for dash lights to cycle, slowly press the accelerator to the floor, hold for 10 seconds, release slowly, turn ignition off, and wait 1 minute before starting.

Wiring & Ground Locations

• (K447) ETC Positive & (K448) ETC Negative Circuits — These are the two wires that control the throttle body motor. On a 5.7L Hemi, they are typically found at Pins 5 and 6 of the 6-pin throttle body connector. They run to the PCM C2 (Black/Orange) connector.. P2100 specifically indicates an open circuit in this motor control path. All voltage, continuity, and resistance tests are performed on these two circuits to isolate the fault between the PCM, wiring, and throttle body.
• PCM C2 Connector — The Powertrain Control Module (PCM) is located in the engine bay. The C2 connector is one of the large multi-pin connectors, typically black with an orange insert.. This is the termination point for the throttle control circuits. Technicians may need to test for signals directly at the PCM connector pins to rule out a PCM failure, though this is rare.
• ECM Ground Strap (Mopar PN 68603896AA) — A primary ground strap connects the battery negative terminal to the chassis/fender area. Additional engine-to-chassis grounds are also present, often near the alternator on the passenger side.. A poor or corroded main ground connection can cause unstable voltage across the entire electrical system, leading to various electronic faults, including ETC errors. Ensuring all grounds are clean and tight is a crucial, though sometimes overlooked, diagnostic step.

Real Owner Repair Stories

• Reddit user in r/ram_trucks (2019 Ram 1500 Rebel) — Truck would not start unless jumped. It would act like it wanted to turn over but wouldn't. An ETC-related code (P2111) was present.
  ❌ Tried (didn't work) Letting the truck run for an extended period after being jumped did not charge the battery enough to allow a restart.
  ✅ What actually fixed it Replacing the vehicle's battery resolved both the no-start condition and the electronic throttle code.

OEM Part Supersession History

• 53034251AB, 53034251AC → 53034251AD — For the 5.7L V8 Hemi engine, part number 53034251AD is the latest revision, replacing older versions. Supersessions typically address reliability issues or manufacturing improvements, which is consistent with the known failures addressed by the TSB.
• 68366240AA, 68366240AB, 68366240AC, 68366240AD → 68603896AA — This is the part number for the ECM ground strap. The multiple revisions suggest improvements to the material or connection points to ensure a reliable ground over the vehicle's life.

Model Year Variations Within This Range

• 2019: The 2019 model year is a transition period. The all-new 'DT' Ram 1500 was sold alongside the previous generation, re-badged as the 'Ram 1500 Classic' (DS). While both can be affected by the P2100 TSB, it is critical to use the vehicle's VIN to ensure the correct throttle body part number is ordered, as other components may differ between the two distinct platforms.