Diagnostic article Generic OBD-II
P037C: Silverado and Sierra harness contact in the 2.7L diagnostic case
GM identifies engine-harness contact areas and a campaign exclusion before applying this P037C-related investigation.
Read before applying this article
Documented application
GM PIT5677E, April 22, 2021: North American 2019 Silverado/Sierra 1500 New Model and 2020–2021 Silverado/Sierra 1500 with 2.7L L3B; VINs covered by Customer Satisfaction Program N192219370 are excluded.
The code alone does not identify a failed part or establish that a vehicle is safe to drive. Confirm the vehicle, reporting module and applicable service procedure.
P037C is included in a broad electrical fault pattern on the 2.7L L3B trucks covered by GM PIT5677E. Possible complaints include no crank, no start, rough running, reduced power, erratic speedometer behavior or blown fuses. The proposed shared cause is engine-harness contact with nearby components, not a conclusion that every listed code identifies a separate failed part.
Check the campaign boundary first
GM explicitly excludes VINs covered by Customer Satisfaction Program N192219370 from this bulletin. Vehicle year and engine alone are therefore insufficient to establish applicability. The workshop must verify the VIN’s program status before using this inspection and protection procedure.
The bulletin identifies contact areas at the camshaft carrier cover, lower air-cleaner housing, generator bracket, left-front coil-spring stud and upper-control-arm bushing. It also explains that normal engine movement can produce contact that is absent during a stationary engine-off inspection. A harness appearing clear at rest does not eliminate all of these possible contact points.
Repair damage and change its exposure
If contact is isolated, the technician inspects for internal conductor damage and repairs confirmed damage using GM wiring procedures. The bulletin then specifies harness-retention and protective-sleeve updates at defined locations. Restoring electrical continuity without addressing the rub point would leave part of the prescribed correction unfinished.
Bring the full scan, fuse findings and the operating conditions that trigger the complaint. P037C alone does not prove harness chafing, and the bulletin does not establish a universal camshaft-system repair. Its useful contribution is a scoped physical inspection and prevention path for a verified multi-system electrical event.
Source and applicability
GM PIT5677E, April 22, 2021: North American 2019 Silverado/Sierra 1500 New Model and 2020–2021 Silverado/Sierra 1500 with 2.7L L3B; VINs covered by Customer Satisfaction Program N192219370 are excluded.
PIT5677E — NHTSA manufacturer communication 10193465, physical PDF pages 1, 2, 3, 4, 5, 6, 7.
Article source documents
Source checks describe how the text was prepared; they do not certify a diagnosis or confirm compatibility with every vehicle using this code.
Original code reference
Dictionary definition
Cold Start Camshaft Profile System Performance
This definition retains its original catalog scope. The article above is limited to its explicitly documented application.
Reference scope
Generic OBD-II definition.
A manufacturer label does not establish the model, year, engine or module to which a diagnosis applies. Read the safety and diagnostic limits.
Definition source
- DTC Database: pinned community code definitions
Source checked · MIT