P0888 on RAM: How to Diagnose & Fix
TCM Power Relay Sense Circuit
1 RAM model · 1 documented issue · 1 critical · $1,500-$4,800 repair
P0888 on RAM by model: symptoms, diagnosis and fix
The 68RFE 6-speed automatic behind the Cummins is prone to torque converter shudder and lockup failure. The factory converter's clutch material and heat control are marginal for the Cummins' torque, so the torque converter clutch (TCC) chatters, slips, or refuses to hold lockup, felt as a low-speed vibration like driving over rumble strips. The TCC regulator valve wears its bore in the valve body, making apply pressure erratic. The resulting heat contaminates the fluid and cascades into planetary and clutch-pack damage. Heat is the number-one killer, especially when towing; fluid temps regularly over 200°F accelerate failure.
Common Symptoms
- Shudder/vibration around 40-55 mph (converter lockup)
- Slipping or flaring on lockup
- High transmission temperatures when towing
- Harsh or delayed shifts
- Burnt-smelling ATF+4 fluid
- Check engine light with TCC codes
How to Fix
Replace the torque converter with a stronger billet/multi-disc unit (e.g., Sun Coast, BD Diesel, or Suncoast triple-disc) rather than another stock converter. Rebuild or upgrade the valve body / TCC regulator valve (Sonnax) to restore correct apply pressure. Add an auxiliary transmission cooler and use the correct ATF+4 fluid, and consider a deep pan and improved fluid capacity for towing. Address early to avoid a full transmission rebuild.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- BD Diesel 1070220X ProForce enhanced-stall 68RFE torque converter
Restrict approval to manufacturer-cataloged 2007.5-2018 Ram 2500/3500 6.7L with 68RFE; verify early-2011 six- versus eight-bolt configuration and core terms. Do not extrapolate seller claims through 2024 without PI-curve/year confirmation.
- Genuine Mopar 68218058AC ATF+4 fluid
ATF+4/MS-9602 applications only; confirm container size, exact service quantity and current service information.
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Sources for this issue (3)
P0888 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P0888 mean on a RAM?
P0888 stands for "TCM Power Relay Sense Circuit." This code sets when the transmission control module (TCM) detects an incorrect voltage on the power relay sense circuit, which monitors whether the TCM power relay is supplying voltage as expected. If the relay or its sense circuit is faulty, the TCM cannot confirm it is properly powered to control the transmission. Symptoms can include shifting problems, the transmission entering failsafe mode, and a check engine light. The fault usually lies in the power relay, the sense wiring, or related connections. On RAM it is documented across 1 model: 2500.
What are the most common causes of P0888?
The most common causes of P0888 are: Faulty TCM power relay, Open, shorted, or corroded sense-circuit wiring, Blown fuse in the power/relay circuit, Poor or loose connector at the relay or TCM, Poor ground connection, Low system voltage, Faulty TCM (less common). The specific cause varies by vehicle.
How much does it cost to fix P0888 on a RAM?
Published repair estimates on RAM range from $1,500 to $4,800 depending on the model and root cause. If an issue mentions a recall or campaign, check your VIN with the manufacturer or NHTSA and confirm eligibility and coverage with a dealer.
Looking for P0888 on a different make?
View P0888 across all makes →Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.