P1635high severityPowertrain

5 Volt Reference 1 Circuit

on 2017 GMC Acadia 2.5L I4 · AWD

What this code means

The PCM detected that the 5-volt reference A circuit voltage is out of tolerance. This circuit provides the sensor feed voltage for multiple sensors including the MAP sensor, TP sensor, EGR valve position sensor, and fuel tank pressure sensor. A fault here can affect multiple systems simultaneously.

Symptoms

Check Engine Light
Engine stalling
Rough idle
Poor performance
Multiple sensor codes may set
Loss of power

Common causes

Short to ground in one of the sensors connected to the 5V reference
Damaged sensor wiring
Faulty sensor drawing excessive current
Defective PCM 5V reference driver
Fuel pump harness shorted to fuel tank pressure sensor

Diagnostic steps

Measure 5V reference voltage at multiple sensors
Disconnect sensors one at a time to isolate short
Inspect fuel pump harness for shorts to FTP sensor
Check sensor wiring for chafing or damage
Test PCM 5V reference output

Repair notes

Disconnect sensors one at a time to find which sensor circuit is pulling the reference low. Inspect fuel pump harness. Repair shorted wiring. This is a root-cause code that can trigger many other sensor DTCs.

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