Powertrain, generic (extended)

P24EF Control Module Wake-up Circuit/Open

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

Some control modules drive a discrete wake-up output that switches other units on before or alongside the network. P24EF reports an open circuit on that line. GM uses it in the HPC2 battery-side processor of its 2016 and 2019 hybrid tables: with the output commanded off, a control voltage between 2.82 and 7.04 V counts as open, because an intact line would be pulled clearly low. The test samples every 12.5 ms and fails when 480 of 560 samples are bad, about seven seconds; it is Type A, so the MIL comes on after one trip. A broken wire, a backed-out pin or a module with a failed output are the typical reasons. The driver may face a module that does not wake up. P24F0 and P24F1 are the low and high faults.

Likely causes

Broken wake-up wire in the harness
Pin pushed back or corroded in a module connector
Wake-up output of the control module defective

Symptoms

  • Malfunction indicator lamp on
  • Connected module stays asleep, with related communication codes

Repair estimate

DifficultyHardWorkshop job
Parts and labour€100–900
Time1–4 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

wake up circuitcontrol modulewiring harness

Related codes

P24F0P24F1

References: gsi.ext.gm.com, gsi.ext.gm.com.