P0748: Pressure Control Solenoid "A" Electrical

What does P0748 mean?

Common causes

• Corroded, fluid-soaked, or unlatched pins at the case connector
• An open or a short in the external control wire, which the Wrangler NAG1 chart tests with the ignition off before the solenoid
• A coil outside the resistance band in this chart — 5.0–5.6 ohms at 20°C for SL1 on the 2012 Tundra A750/A760 and the 2012 RAV4 procedure, and a different band everywhere else
• The valve-body harness, replaced with the solenoid on the 8-speed vehicles in Hyundai/Kia TSB 23-AT-003H-1
• A module driver, after the wire and the coil match the chart
• The wrong solenoid ordered because 'A' was assumed to be the line-pressure solenoid

Symptoms

• Check engine light with P0748 stored
• Harsh or late shifts, on a unit whose failed electrical solenoid is the one that sets line pressure
• One clutch that does not apply, on a unit where solenoid A is an on/off clutch solenoid such as Toyota SL1
• The failsafe gear this calibration holds
• A circuit test that fails every time, rather than only on a hot road test
• No change from a fluid service, because an open wire is not a fluid condition

Diagnostic steps

1. 1.Confirm the part. On the 2012 Tundra A750E/A760E and the 2012 RAV4, P0748 is shift solenoid SL1. On the Ford 6F35, P0748 is in the line-pressure pinpoint with P0960, P0962, and P0963. On the 2012 Wrangler NAG1 chart it is the modulator pressure solenoid. Order the part the chart names.
2. 2.Ignition off. Disconnect the transmission connector and inspect both halves. Then measure the coil from that connector against this chart. The 5.0–5.6 ohm band at 20°C is the SL1 figure in the Toyota procedures named above, together with an insulation check to the case. Do not use it on a 6F35 line-pressure solenoid.
3. 3.With the solenoid unplugged from the module, check the control wire for an open and for a short to ground or power. The Wrangler chart does this before it condemns the solenoid. Hyundai/Kia TSB 23-AT-003H-1 inspects the external harness before it replaces the solenoid and the valve-body harness on the 8-speeds it lists.
4. 4.Do not power a solenoid lead from the battery to see if it clicks unless this procedure says to. A current-controlled solenoid and an on/off solenoid are different parts.
5. 5.If the coil and the external wire are in range, the remaining branch is the internal harness or the module, in the order the chart gives. On the TSB 23-AT-003H-1 vehicles the internal harness is replaced with the solenoid, and the module comes after a second return of the code.
6. 6.Pan-off work waits until those checks point inside. Support the vehicle on a lift or stands and let the fluid cool. Fluid that goes back in is part of closing the pan. It does not repair an open circuit.
7. 7.Clear the code and rerun the circuit test. Then record a drive, with a passenger reading the tool, and confirm the shift or the pressure command this solenoid is responsible for.

Repair cost

$300 – $900 (simple solenoid replacement)

AutoZone's simple solenoid replacement is $300–$900 parts and labor. That is this pair. A Toyota SL1, a 6F35 line-pressure solenoid, and a NAG1 modulator solenoid are different parts, and this band does not separate them. No national total was found for a connector repair, so a lower connector-only price is not printed. Hyundai/Kia TSB 23-AT-003H-1 also replaces the valve-body harness with the solenoid on the 8-speeds it lists. That harness is not a separate line in the AutoZone sentence. A rebuild at $1,800–$3,500 and a replacement at $4,000–$8,000 are outside the pair. RepairPal's fluid change averages $294–$356, updated 3 September 2026, and is not a repair for an open or a short.

DIY vs shop

Leave this one to a qualified shop. The barrier here is internal hydraulic and mechanical work, fluid handling at temperature, and an adaptive relearn afterwards without which a correct repair still shifts badly. DIY attempts often produce a more expensive problem than the original code.

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