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.
Pinpoint Test E: No Communication With The Electronic Automatic Temperature Control (EATC) Module
- E1 CHECK CIRCUIT 57 (BK) FOR AN OPEN
- Disconnect: EATC Module C228a.
- Measure the resistance between EATC module C228a-3, circuit 57 (BK) and ground.
- Is the resistance less than 5 ohms?
Yes : GO to E2.
No : REPAIR circuit 57 (BK) for an open. TEST the system for normal operation.
- E2 CHECK CIRCUIT 1566 (RD/YE) FOR B+
- Measure the voltage between EATC module C228a-2, circuit 1566 (RD/YE) and ground.
- Is the voltage reading B+?
Yes : GO to E3.
No : VERIFY the central junction box (CJB) fuse 3 (10A) is OK. If OK, REPAIR circuit 1566 (RD/YE) for an open. TEST the system for normal operation.
- E3 CHECK CIRCUIT 1812 (BN/WH) FOR B+
- Key in ON position.
- Measure the voltage between EATC module C228a-16, circuit 1812 (BN/WH) and ground.
- Is the voltage reading B+?
Yes : REFER to MODULE COMMUNICATIONS NETWORK to diagnose the network concern.
No : VERIFY the central junction box (CJB) fuse 2 (10A) is OK. If OK, REPAIR circuit 1812 (BN/WH) for an open. TEST the system for normal operation.
NO RELATED
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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.