Notes

Engine Coolant Temperature Sensor: Notes — 1994 Audi S4 Service Manual & Component Testing >> Engine Sensors & Switches >> Engine Coolant Temperature Sensor >> Notes Engine Coolant Temperature Sensor: Notes NOTE: All voltage and continuity tests should be performed with a Digital Volt-Ohmmeter (DVOM) with a minimum 10-megohm input impedance, unless specifically stated differently in testing procedures. For help with diagnostic testing. See WIRING DIAGRAMS. Location of Engine Coolant Temperature (ECT) sensor and harness connection. See COMPONENT LOCATIONS. Allow engine to cool to room temperature approximately 68°F (20°C). Disconnect ECT sensor harness connector. Using DVOM switched to resistance range. Connect DVOM to ECT sensor terminals No. 1 and 2, using adapter cables from (VW 1594) connector test kit. See Fig 1. Resistance must be approximately 1500-3000 ohms. See ECT SENSOR RESISTANCE table. If resistance is incorrect, replace ECT sensor. If YES: Check wiring between sensor and Engine Control Module (ECM) as follows: Connect (VAG 1598) test box to ECM wiring harness using (VAG 1598/5) adaptor cable. See CONNECTING VAG 1598 TEST BOX. ECM is not connected. Check continuity between socket 45 of test box and terminal No. 1 of ECT sensor harness connector (Resistance must be 1.0 ohm maximum). See Fig 2. Check continuity between socket 30 of test box and terminal No. 2 of ECT sensor harness connector (Resistance must be 1.0 ohm maximum). See Fig 2. Check both wires for short circuit to each other. Check for a short or open circuit between sensor harness connector and ECM harness connector (terminal No. 30 and/or terminal No. 45). See Figure. If problem exist, repair as necessary. If circuit are okay, replace ECM. After replacement of ECM, see ECM IDENTIFICATION and ECM CODING under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS article. See WIRING DIAGRAMS. ECT SENSOR RESISTANCE Temperature Ohms 68°F (20°C) Approx. 2500 176°F (80°C) Approx. 330 Fig 1: Identifying Engine Coolant Temperature Sensor Harness Connector Terminals [IMAGE: http://127.0.0.1:8080/images25/G00177361/] Courtesy of AUDI OF AMERICA, INC. Fig 2: Identifying ECT Sensor, EVAP Canister Purge Valve, Fuel Injector, HO2S Heater 2-Pin (Black) & IAC Wiring Harness Connector Terminals [IMAGE: http://127.0.0.1:8080/images25/G96D09931/] Courtesy of AUDI OF AMERICA, INC.