P0888: How to Diagnose & Fix — TCM Power Relay Sense Circuit
2 vehicles · 2 makes · $200-$4,800 repair
How to diagnose and fix P0888: most-reported vehicles
Ranked by owner reports. Each card gives the symptoms, how to confirm the cause, the fix, parts and sources for that vehicle.
RAM 2500 · 2007–2024
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.
As an Amazon Associate, we earn from qualifying purchases; other part links may also earn au7o a commission. Confirm fitment by VIN before buying.
Sources for this issue (3)
Dodge Dakota · 1997–2011
The 42RE (4-speed) and 45RFE/545RFE (5-speed) automatic transmissions in the Dakota suffer from overdrive solenoid failures. The overdrive solenoid sticks or fails electrically, preventing the transmission from engaging overdrive or causing it to drop out of overdrive unexpectedly. This increases highway fuel consumption and engine RPM. The issue is exacerbated by old, contaminated transmission fluid.
Common Symptoms
- Transmission will not shift into overdrive
- Overdrive drops out at highway speeds
- Higher than normal RPM at highway cruising speed
- Check engine light with overdrive codes
- Increased fuel consumption on highway
How to Fix
Replace the overdrive solenoid and governor pressure solenoid as a pair — they are accessed by dropping the transmission pan and valve body. Use Mopar ATF+4 (68218058AC) exclusively. For the 42RE, the solenoid pack is inexpensive ($40-$80) but labor is 2-3 hours. For the 45RFE/545RFE, replace the entire solenoid block assembly. Regular fluid changes every 30,000 miles help prevent recurrence.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- Crown 52118500AB transmission overdrive solenoid
Overdrive-solenoid replacement only after diagnosis confirms this component Fitment: Manufacturer application lists 2000-2003 Dakota with 42RE/46RE; it does not cover 1997-1999 or an RFE transmission Live manufacturer product page when c…
- Remanufactured OE white-connector RFE solenoid block
Replace the whole RFE solenoid block when electrical/hydraulic diagnosis proves the block Fitment: Vendor lists 2004-2010 Dodge Dakota and 2011 Ram Dakota; confirm connector color, transmission family and OE-number interchange Live direc…
- 45RFE/545RFE 4WD sump and cooler-return filter kit
Replace both filters during RFE solenoid-block service Fitment: 4WD 45RFE/545RFE only; 2WD and 42RE/46RE use different filter hardware Live direct US product page with quantity/order control when checked
- Mopar 68218057AC ATF+4 fluid
Approved service fluid after the transmission-specific repair Fitment: Use exact service-fill quantity for the installed transmission and repair state Live Mopar direct product page when checked
Sources for this issue (1)
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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?
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.
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?
Repair costs for P0888 range from $200 to $4,800, depending on the vehicle and root cause.
Which vehicles are affected by P0888?
Au7o has documented P0888 across 2 vehicle models from 2 manufacturers: Dodge, RAM.
Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.