Diagnostic article Generic OBD-II
P0701: Allison range inhibition and low pump-pressure diagnosis
GM directs technicians to diagnose P0701 first when it accompanies certain engagement and ratio faults on listed Allison-equipped trucks.
Read before applying this article
Documented application
GM PIP4379N, September 12, 2018: 2001–2019 Silverado and Sierra 2500/3500; 2003–2010 Kodiak and TopKick, with transmissions M74 or MW7.
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.
P0701 deserves priority when one of the listed Allison-equipped GM trucks has delayed or absent drive or reverse engagement, or range inhibition. GM PIP4379N connects that symptom pattern with possible low or absent pump pressure caused by a failure to establish or retain pump prime. Cold starts can make the complaint more noticeable.
Diagnose the pressure context before individual companion codes
The bulletin lists several possible ratio, solenoid and pressure-related entries. When P0701 accompanies them, GM directs the technician to begin with the P0701 service procedure. Treating each companion code as an independent failed component can overlook the shared pressure problem.
Fluid level must be established with the specified hot-check procedure. A quick cold reading is not equivalent. GM also asks technicians to consider recent fluid or filter service, pan removal, leaks and extended storage, because those histories can be relevant to loss of prime.
What changes the next inspection
If the level has been correctly verified and faults return during a cold start, the bulletin directs inspection of the internal suction filter for cracks. If no other cause is found, it identifies a lube regulator valve in the pump cover that can stick because of debris. These are staged investigations, not instructions to replace all suspected parts.
Record the temperature and engagement delay, plus the date of any transmission service. Internal inspection and controlled pressure diagnosis belong with a qualified transmission technician. GM specifically cautions that replacing the transmission control module is unlikely to correct the listed codes or low main-line pressure. The code does not establish that a complete transmission replacement is needed.
Source and applicability
GM PIP4379N, September 12, 2018: 2001–2019 Silverado and Sierra 2500/3500; 2003–2010 Kodiak and TopKick, with transmissions M74 or MW7.
PIP4379N — NHTSA manufacturer communication 10145478, physical PDF pages 1, 2.
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
Transmission Control System Range/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