Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSCHEVROLET2020EXPRESS 2500 LS, 2.8L ENG VIN 1REPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 102 (ENGINE CONTROLS AND FUEL - 6.0L (L96 LC8) - DIAGNOSTIC INFORMATION AND PROCEDURES (1 OF 2))DIAGNOSTIC INFORMATION AND PROCEDURESDTC P025A (CHASSIS CONTROL MODULE)CIRCUIT/SYSTEM TESTING
2020 Chevrolet Express 2500 LS, 2.8L Eng VIN 1
Circuit/System Testing
2020 Chevrolet Express 2500 LS, 2.8L Eng VIN 1SECTION Circuit/System Testing
WARNING: This page is about a different car, the 2019 GMC Savana 3500, 2019 GMC Savana 2500, 2019 Chevrolet Express 3500, and 2019 Chevrolet Express 2500. However, it is still accessible from the selected car via links, so may be relevant.
- Ignition/Vehicle & All vehicle systems - Off
- Disconnect the electrical connector: K38 Chassis Control Module
- Connect a test lamp between the test points: Control circuit terminal 20 & Ground
- Perform the scan tool control function: Fuel Pump Enable Command @ Engine Control Module - On and Off
Verify the test lamp turns On and Off.
- If the test lamp is always Off
- Ignition/Vehicle - Off & Remove - Test lamp
- Disconnect the electrical connector: K20 Engine Control Module
- Ignition - On / Vehicle - In Service Mode
- Test for less than 1 V between the test points: Control circuit terminal 20 @ K38 Chassis Control Module & Ground
- If 1 V or greater - Repair the short to voltage on the circuit.
- Go to next step: If less than 1 V
- Ignition/Vehicle - Off
- Test for less than 2 ohms between the test points: Control circuit terminal 20 @ K38 Chassis Control Module & The other end of the circuit
- If 2 ohms or greater - Repair the open/high resistance in the circuit.
- If less than 2 ohms - Replace the component: K20 Engine Control Module
- If the test lamp is always On
- Ignition/Vehicle - Off & Remove - Test lamp
- Disconnect the electrical connector: K20 Engine Control Module
- Test for infinite resistance between the test points: Control circuit terminal 20 @ K38 Chassis Control Module & Ground
- If less than infinite resistance - Repair the short to ground on the circuit.
- If infinite resistance - Replace the component: K20 Engine Control Module
- Go to next step: If the test lamp turns On and Off
- Test or replace the component: K38 Chassis Control Module
NOTE:
It may take up to 2 min for all vehicle systems to power down before an accurate ground or low reference circuit continuity test can be performed.
RENDER: 1.0x
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.