P0748 on GMC
Pressure Control Solenoid "A" Electrical
P0748 on GMC vehicles indicates pressure control solenoid "a" electrical. Au7o has documented this code across 1 GMC model — most commonly on Savana. 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. Typical repair costs on GMC range from $1,800 to $3,200, depending on the specific model and root cause.
Common Causes of P0748
- •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)
P0748 on GMC by Model
GMC Savana(1 issue)
- 4L60E/4L65E Automatic Transmission 3-4 Clutch Pack Burnup and Overdrive Slip (Savana 1500)1996-2014
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.
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What does P0748 mean on 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 specifically, this code is documented across 1 model.
What causes P0748 on GMC vehicles?▼
Common causes on GMC: 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. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix P0748 on a GMC?▼
Repair costs on GMC range from $1,800 to $3,200, depending on the specific model and root cause.
Which GMC models have P0748 documented?▼
Au7o has documented P0748 on 1 GMC model: Savana.