What Does P0948 Mean?
DTC P0948 indicates the hydraulic pump relay circuit voltage is higher than expected. The TCM detects an abnormally high voltage on the relay circuit, which may indicate the relay is stuck energized, the control wire is shorted to battery voltage, or there is a feedback voltage issue. This can cause the hydraulic pump to run continuously or the TCM to lose proper control of pump operation.
Safety Warning
A high relay circuit can cause the hydraulic pump to run uncontrolled, potentially leading to excessive pressure that could damage hydraulic seals and actuators. A continuously running pump will also drain the battery and may overheat. This requires prompt attention to prevent cascading damage.
Common Causes
30%
Relay contacts welded closed, causing continuous pump operation
25%
Relay control wire shorted to battery voltage in the harness
15%
Back-feed voltage from the pump motor circuit through the relay
15%
Corroded relay socket creating a voltage bridge between terminals
15%
TCM relay driver transistor shorted in the on-state
Diagnostic Steps
1
Step 1: Check if the hydraulic pump is running continuously, even with the key off. This indicates welded relay contacts. Remove the relay immediately to prevent pump burnout.
2
Step 2: Remove the relay and test it. Verify the contacts open fully when the coil is de-energized. If contacts remain closed, the relay is stuck and must be replaced.
3
Step 3: With the relay removed, measure voltage on the relay control pin at the socket. If battery voltage is present when the TCM is not commanding the relay, trace the wire for a short to B+.
4
Step 4: Inspect the relay socket for corrosion or debris that could bridge between the power input and control terminals.
5
Step 5: Install a new relay and verify the pump only operates when commanded by the TCM. Monitor the relay circuit voltage to confirm it returns to normal operating parameters.
Estimated Repair Cost
$80 - $500
Parts + labor, varies by vehicle and location
DTC P0948 indicates the hydraulic pump relay circuit voltage is higher than expected. The TCM detects an abnormally high voltage on the relay circuit, which may indicate the relay is stuck energized, the control wire is shorted to battery voltage, or there is a feedback voltage issue. This can cause...
The most common cause of P0948 (Hydraulic Pump Relay Circuit High) is: Relay contacts welded closed, causing continuous pump operation
Typical repair costs for P0948 range from $80 to $500, depending on the vehicle, location, and whether you do it yourself or go to a shop.
A high relay circuit can cause the hydraulic pump to run uncontrolled, potentially leading to excessive pressure that could damage hydraulic seals and actuators. A continuously running pump will also drain the battery and may overheat. This requires prompt attention to prevent cascading damage.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0948 to identify the root cause.
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Quick Info
Category
Powertrain
System
Transmission / Clutch Hydraulic System
Difficulty
Type
Generic (SAE)
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