2016 Ram ProMaster 62TE transmission diagnostic
Analysis of OBDLink MX+ logs from 2026-05-20 (town loop, 1,502 samples) and 2026-05-22 (highway with mechanic Scott Andersson, 1,221 samples). The van entered limp mode once on 2026-05-16 and has not recurred. Codes pulled at the incident: P0846, P0731, P0792.
Incident
On 2026-05-16, the van was traveling northbound on the highway near San Jose, exited, and stopped at a stoplight. When the light changed, Drive would not pull — the transmission held against rolling backward on a slope for approximately five seconds, then dropped to neutral. Three codes were read on the shoulder and cleared, the battery was disconnected for fifteen minutes, and the van engaged Drive and was driven 200 miles to Santa Barbara at 60–65 mph without recurrence. No limp event has occurred since, including a deliberate wide-open-throttle pull to redline with a mechanic in the passenger seat on 2026-05-22.
Methods
Codes
P0846— cleared, did not return- Transmission Fluid Pressure Sensor/Switch B Range/Performance. A pressure-switch fault. On the 62TE, all five pressure switches reside inside the solenoid pack.
P0731— returned- Gear 1 Incorrect Ratio. Set when the TCM's computed gear ratio diverges from the commanded gear. Can be triggered by a pressure-switch glitch (transient) or by real clutch slip (progressive).
P0792— returned- Intermediate Shaft Speed Sensor A Circuit Range/Performance. Can be set by intermediate-shaft sensor or wiring fault, or by clutch slip causing the intermediate shaft to spin faster than commanded. The transfer-shaft signal has been alive and clean in both subsequent logs, including under WOT.
The three codes are interrelated on the 62TE platform. The combination — one cleared, two returned — is documented in the 62TE service literature as a pressure-switch transient signature (Cherish Your Car, Sonnax, Transmission Digest, Monster Transmission). Limp-in trip requires four ratio-error events in one drive cycle; a single transient is enough to set these codes without recurring.
Wide-open-throttle pull
Wide-open-throttle event on the 5/22 highway log. Engine RPM, turbine RPM, output RPM, and vehicle speed across the 14-second window from throttle application through 6-5 settle-back. Annotated events: throttle stomp (t=306.3), 3→2 kickdown (t=307.0), redline approach (t=309.4), 2→3 upshift (t=310.0). Peak sample: engine 6,112 RPM, turbine 5,919 RPM, slip ~3%, gear 2nd, TPS 4.33 V, line pressure 2.53 V.
Gear-ratio observation vs published reference
Observed turbine/output ratio per sample, grouped by reported gear, plotted against published 62TE ATSG reference ratios. The observed ratios sit a uniform −5.4% below published across every gear. Clutch slip would vary by gear (different clutch packs engaged on different shifts); a uniform constant-fraction offset is consistent with a sensor or PID scaling artifact, not slippage.
Coastdown shift patterns
Three deceleration-to-stop events from the 5/22 log. Each event steps 4th → 3rd → 1st, with 2nd skipped. The chief reported symptom is a rough 3→2 downshift in low-speed driving; no 3→2 event occurred in 759 seconds of driving, so this log neither confirms nor exonerates the persistent symptom.
Pressure-switch trace
Five pressure switches (LR, 2-4, OD, LC, DC) across the 5/22 highway drive, downsampled to ~300 cells. Switches transitioned cleanly on every shift across the drive, including through the WOT pull. No flicker or chatter observed.
Symptoms
| Symptom | Data verdict / likely cause |
|---|---|
| One-time limp event (highway, 2026-05-16) | Transient. Did not recur in 27 minutes of subsequent logging including WOT to redline. Consistent with documented 62TE solenoid-pack pressure-switch transient. |
| Clunky 3→2 downshift in town (worsening) | Not exercised by the available logs (coastdowns skipped 2nd). Literature attributes to age-related low-reverse piston housing gasket shrinkage or valve-body SSV bore wear. |
| Heavy clunk Park → Drive in parking lots | Not directly captured. PCM calibration / adaptive shift values are a possible contributor; reflash and Quick Learn are documented mitigations. |
| Bouncy low-speed uphill acceleration | Not visible to OBD data. Possible drivetrain, mount, or torque-converter contribution. |
| Sticky shifter in Drive | PRNDL signal reads cleanly across all logs; transmission range sensor is not the cause. Likely mechanical linkage (cable, bushings, detent). |
Next steps
- Hot ATF+4 level and condition check using a 62TE-appropriate measuring dipstick (Mopar/Miller 9336A or Dorman 917-327). The ProMaster uses a capped filler tube.
- Quick Learn / adaptive relearn via an FCA-capable scan tool.
- Bench resistance test of the solenoid pack (shift solenoids ~1.8Ω, line-pressure solenoid ~4.9Ω, pressure switches ~300Ω).
- Solenoid pack replacement only if bench test out of spec.
- Valve body inspection / Transgo SK-62TE shift kit / Sonnax SSV repair if the persistent 3→2 clunk survives steps 1–4.
- Low-reverse piston housing gasket replacement (teardown) only if all preceding steps fail to address the persistent low-speed downshift symptom.