P0748 on GMC: How to Diagnose & Fix
Pressure Control Solenoid "A" Electrical
1 GMC model · 1 documented issue · 1 critical · $1,800-$3,200 repair
P0748 on GMC by model: symptoms, diagnosis and fix
The light-duty Savana 1500 uses the 4L60E (later 4L65E) four-speed, not the heavy-duty 4L80E fitted to 2500/3500 models, and it is the weak link of the lineup. In van duty the converter clutch and overdrive cycle constantly at city speeds, and the 3-4 clutch pack and its apply seals cook. Owners describe a van that drives normally for a few miles and then flares between 3rd and 4th, or revs like it is in neutral once hot. Forum reports on 1996-2002 5.0L/5.7L and 2003-2014 5.3L 1500 vans repeat the same pattern; a plugged filter and burned fluid are usually found at teardown. This is a 1500-specific chapter - it is not the 4L80E story and should not be read across to the 2500/3500.
Common Symptoms
- Engine revs but van does not accelerate
- Slipping or flaring between 3rd and 4th gear
- Transmission works when cold, slips once hot
- Harsh or delayed 1-2 shift
- Burned-smelling dark transmission fluid
- Overdrive hunting in and out at city speeds
How to Fix
No recall or GM special coverage exists. The real fix is a rebuild or reman 4L60E/4L65E with upgraded 3-4 clutch pack (more frictions, updated apply piston) and a new torque converter; a shop rebuild typically runs $1,800-$3,200 installed. Preventively, shorten the fluid-and-filter interval to roughly 50,000 miles and add an auxiliary transmission cooler - van duty cycles run the fluid far hotter than the truck the box was calibrated for. Early slip caught with only a plugged filter has occasionally been cured with a fluid and filter service, but once the 3-4 pack is burned only a rebuild corrects it.
Sources for this issue (3)
P0748 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 P0748 mean on a GMC?
P0748 stands for "Pressure Control Solenoid "A" Electrical." P0748 is a generic powertrain code meaning the transmission control module has detected an electrical fault — voltage or resistance out of the expected range — in the circuit for pressure control solenoid "A". This solenoid regulates hydraulic line pressure inside an automatic transmission, adjusting how firmly the clutches and bands apply based on speed, load, and throttle position. When the computer can't control the solenoid electrically, the transmission often defaults to maximum line pressure or limp mode, so you may feel harsh or erratic shifts, slipping, delayed engagement when shifting into Drive, or being locked into a single gear. Because it is an electrical-circuit code, the fault is usually in the solenoid itself or its wiring rather than a purely hydraulic problem, though contaminated fluid can damage the solenoid. Continuing to drive with slipping and overpressure shifts can overheat the transmission and lead to expensive internal damage, so this should be repaired promptly. On GMC it is documented across 1 model: Savana.
What are the most common causes of P0748?
The most common causes of P0748 are: Failed pressure control solenoid A (open or shorted solenoid windings), Damaged, frayed, or shorted wiring in the solenoid circuit, including the transmission case connector, Corroded or loose electrical connectors at the transmission harness, Low, dirty, or contaminated transmission fluid degrading or sticking the solenoid, Clogged transmission filter or debris in the valve body hydraulic passages, Faulty transmission control module or PCM driver circuit (rare). The specific cause varies by vehicle.
How much does it cost to fix P0748 on a GMC?
Published repair estimates on GMC range from $1,800 to $3,200 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 P0748 on a different make?
View P0748 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.