# Service bulletin 18\-022\-21

A bulletin is a manufacturer's communication to its dealers, as NHTSA indexes it. The summary is NHTSA's. The document is the manufacturer's: read it at NHTSA. A bulletin is not a recall, and listing a model year does not mean every vehicle of it is concerned.

- Type: Service bulletin
- NHTSA id: 10188820
- Published by NHTSA: 2021\-03\-15
- Manufacturer's number: 18\-022\-21
- Manufacturer's date: 2021\-02\-17
- NHTSA component: POWER TRAIN

## NHTSA's summary

Flash: Powertrain Control Module \(PCM\) Updates This bulletin involves reprogramming the PCM with the latest available software. Customers may experience a Malfunction Indicator Lamp \(MIL\) illumination. Upon further investigation the technician may find that the one or more of the following DTCs have been set:P0300 \- Multiple Cylinder Misfire. P0301 \- Cylinder 1 Misfire. P0302 \- Cylinder 2 Misfire. P0303 \- Cylinder 3 Misfire. P0304 \- Cylinder 4 Misfire. P0305 \- Cylinder 5 Misfire. P0306 \- Cylinder 6 Misfire. P0307 \- Cylinder 7 Misfire. P0308 \- Cylinder 8 Misfire. The customer may also experience one or more of the following:Rough idle/misfire only after cold start Auto Park system is unable to be manually over\-ridden after an Auto Park event. Auto Park disabled message will not display in cluster. ECO light does not illuminate in the cluster when Multiple Displacement System \(MDS\) is active\(EMEA, LATAM and APAC\). 2\-3 kph \(1.3\-1.9 mph\) difference between cruise set speed and the actual vehicle speed\(EMEA, LATAM and APAC\). Bump sensation during a coast down with light acceleration. Abnormal vibration when accelerating lightly during stop and go driving conditions.

## The document

- [NHTSA's copy of the document (PDF)](https://static.nhtsa.gov/odi/tsbs/2021/MC-10188820-0001.pdf)
- [If that address does not open, try this one](https://static.nhtsa.gov/odi/tsbs/2021/MC-10188820-9999.pdf)

The document is the manufacturer's. This site does not hold it.

## Components

Transmission and driveline

## Trouble codes named

P0300, P0301, P0302, P0303, P0304, P0305, P0306, P0307, P0308

## Vehicles listed

- 2020 RAM 1500

## Recalls for the same vehicles and component

- [2020401](/recalls/tc/2020401.md), 2020-08-28: Powertrain

## Other bulletins for the same vehicles and component

- [S2621000004](/bulletins/11038329.md), 2026-10-07, Service bulletin: POWER TRAIN. The Customer May Complain About a Popping Noise, Grinding Noise, or an Intermittent No Reverse or Forward Transmission Engagement. The Tech May Find Damaged and/or Worn Transmission Output Shaft Splines \(850RE Transmission Only\)
- [S2621000003 REV.A](/bulletins/11030138.md), 2026-03-18, Service bulletin: POWER TRAIN. The vehicle will exhibit a service transmission/check engine warning indicator for the following transmission models: 845RE, 8HP45, 850RE, 8HP50, 8HP70, 8HP75, 8HP75\-PHEV, 8HP75\-LCV, 8HP90, 8HP95. Transmissions may exhibit the following diagnostic codes: P07E4, P1DB2, P0716, P1B14, P0733, P1D90, P1DB7, P1B13.
- [S2621000003](/bulletins/11029770.md), 2026-03-05, Service bulletin: POWER TRAIN. Service transmission/check engine warning indicator for the 850RE, 8HP50, 8HP70, 8HP75, 8HP75\-PHEV transmissions that have fault codes P07E4, P1DB2, P0716, P1B14, P0733, P1D90, P1DB7, P1B13.
- [03\-008\-25](/bulletins/11023321.md), 2025-09-24, Service bulletin: POWER TRAIN. Rear Axle Vibration Shudder Or Chatter Customers may experience the following: ● A chatter, shudder, or vibration from the rear axle during turns. NOTE: This may happen more as the vehicle ages, especially if the vehicle is used extensively for towing or hauling heavy loads. The cause of the concern may be due to degradation of the rear axle fluid. It is very important to follow the routine maintenance schedules on these vehicles when it comes to changing the rear axle fluid if the vehicle is used primarily for towing or hauling heavy loads. If you experience a vehicle with the above condition, please perform the proper maintenance procedures for the rear axle and replace the fluid first before replacing any hardware components. NOTE: This service bulletin is only applicable to vehicles that have no history of an axle fluid replacement. If the vehicle usage includes police, taxi, fleet, off\-road or frequent trailer towing, regular axle fluid changes are required every 3 years or 30,000 miles \(whichever comes first\) per the Maintenance Schedule in the vehicle Owner's Manual. This bulletin involves changing the rear axle lube to possibly address a chatter, shudder or vibration.
- [9100627](/bulletins/11020855.md), 2025-07-23, Service bulletin: POWER TRAIN. To inform dealers about the 850RE valve body PN: R8348504A connector: the original 16\-pin connector included six pins that were not used in this application. To simplify the design, the connector has been optimized and updated to a 10\-pin configuration.
- [21\-029\-25 REV. A](/bulletins/11020637.md), 2025-07-09, Service bulletin: POWER TRAIN. 8HP75 D Clutch Repair Customers must experience a Malfunction Indicator Lamp \(MIL\) illumination and the vehicle must have at least 11,265 km \(7,000 mi.\) and exhibit/set one or more of the following Diagnostic Trouble Codes \(DTCs\): ● P0733\-00 \- Gear 3 Shift Incorrect Ratio. ● P1DA8\-00 \- Incorrect Gear Ratio Clutch A B or D Defective. ● P1D92\-00 \- Incorrect Gear Ratio \- Clutch 4 Defective. Customers may also comment on the following: ● Vehicle enter limp home mode. This bulletin involves replacing the D clutch.
- [21\-009\-25 REV. C](/bulletins/11020636.md), 2025-07-09, Service bulletin: POWER TRAIN. 850RE D Clutch Repair Customers must experience a Malfunction Indicator Lamp \(MIL\) illumination and the vehicle must have at least 11,265 km \(7,000 mi.\) and exhibit/set one or more of the following Diagnostic Trouble Codes \(DTCs\): ● P0733\-00 \- Gear 3 Shift Incorrect Ratio. ● P1DA8\-00 \- Incorrect Gear Ratio Clutch A B or D Defective. ● P1D92\-00 \- Incorrect Gear Ratio \- Clutch 4 Defective. Customers may also comment on one or more of the following: ● Transmission slips when shifting. ● Vehicle will not move in reverse. ● Vehicle will not shift higher than third gear This bulletin involves replacing the D clutch.
- [03\-004\-25](/bulletins/11018463.md), 2025-05-19, Service bulletin: POWER TRAIN. "Front Drive Unit Vibrates Customers may experience the following: ● Vibration in the front of the vehicle from the front drive unit This bulletin involves replacing the right front output shaft."
- [9100570](/bulletins/11018453.md), 2025-05-19, Service bulletin: POWER TRAIN. "Transmission Fluid Please note fluid color/condition/odor is NOT an indicator of transmission health and should not be used as the reason for unit replacement. Visible ""glitter"" or debris in the pan does not justify complete unit replacements."
- [9100534 Rev 1](/bulletins/11018452.md), 2025-05-19, Service bulletin: POWER TRAIN. Transmission "Transmission For transmission concerns related to DTCs P0733\-00, P1DA8\-00, and/or P1D92\-00, a repair is available, and transmission replacement is NOT required. Please reference TSB 21\-009\-25 Rev. A, for details on D\-clutch replacement. Please also note, visible ""glitter"" or debris in the pan and fluid color/condition/odor is NOT an indicator of transmission health and should not be used as the reason for unit replacement. Complete unit replacements instead of repairs for these DTCs may be subject to chargeback."

JSON: [/v1/bulletins/10188820](/v1/bulletins/10188820)

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