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Home >> Toyota >> 2001 >> Sienna CE >> Repair and Diagnosis >> External Pages >> Different car >> Section 154 (Engine Immobilizer Systems) >> Diagnostic Tests >> DTC B2798: Communication Malfunction No. 2 >> Diagnostic Procedure

Diagnostic Procedure

WARNING: This page is about a different car, the 2002 Toyota Avalon. However, it is still accessible from the selected car via links, so may be relevant.
  1. Check transponder key coil. See TRANSPONDER KEY COIL  under COMPONENT TESTS. If transponder key coil is okay, go to next step. If transponder key coil is defective, replace transponder key coil. See TRANSPONDER KEY COIL  under REMOVAL & INSTALLATION. After repairs have been made, perform confirmation test. See CONFIRMATION TEST  under SYSTEM TESTS.
  2. Check wiring harness and electrical connectors between transponder key amplifier and ECM. See ANTI-THEFT in SYSTEM WIRING DIAGRAMS article. See Figure. Transponder key amplifier is located near upper steering column bracket and ECM is located behind glove box and has 5 electrical connectors. See Figure. If wiring harness and electrical connectors are okay, go to next step. If wiring harness or electrical connectors are defective, repair as necessary. After repairs have been made, perform confirmation test. See CONFIRMATION TEST  under SYSTEM TESTS.
  3. Replace transponder key amplifier with a known-good unit. See TRANSPONDER KEY AMPLIFIER  under REMOVAL & INSTALLATION. Check system operation. If engine still will not start after replacing original transponder key amplifier, go to next step. If engine starts after replacing original transponder key amplifier, no further testing is required at this time, as the original transponder key amplifier was defective. After repairs have been made, perform confirmation test. See CONFIRMATION TEST  under SYSTEM TESTS.
  4. Check Engine Control Module (ECM) ground circuits. See ANTI-THEFT in SYSTEM WIRING DIAGRAMS article. If ground circuits are faulty, repair and retest system. If ground circuits are okay, substitute original ECM with a known-good unit and recheck system operation. If system operates properly, original ECM was defective. If system still does not operate properly, perform ECM pin voltage check. See PIN VOLTAGE TESTS . Check wiring harness and electrical connectors for an intermittent problem. Repair wiring harnesses or connectors as necessary. If voltage values, harnesses and connectors are okay, replace ECM. After repairs have been made, perform confirmation test. See CONFIRMATION TEST .
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