G - TESTS W/CODES 1995 Volvo 850 1995 ENGINE PERFORMANCE Volvo … SELF-DIAGNOSTIC SYSTEM RETRIEVING CODES CAUTION: Self-diagnostics for fuel injection and … If no fault codes are present, proceed to the H - TESTS W/O CODES article for diagnosis by symptom (i.e., ROUGH IDLE, NO START, etc.). NOTE: All voltage tests should be performed using a Digital Volt-Ohmmeter (DVOM) with a minimum 10-megohm input impedance, unless stated otherwise in testing procedures. SELF-DIAGNOSTIC …

diagnosis. Once function selector cable has been inserted in correct socket, depress button and keep depressed for more than one second (but not more than 3 seconds). Observe LED and count number of flashes to determine diagnostic trouble code, as faults stored in Electronic Control Unit (ECU) memory are read by observing LED flashes. If LED does not flash, see DIAGNOSTIC UNIT “A” LED DOES NOT FLASH. Diagnostic systems for fuel injection and ignition each store 13 codes. All codes contain 3 digits (example: 4-1-3). Since all codes have 3 digits, each code requires 3 series of flashes. A 3-second interval separates each series of flashes. See the appropriate TROUBLE CODE DEFINITION table. TROUBLE CODE IDENTIFICATION TROUBLE CODE DEFINITION - FUEL INJECTION SYSTEM (1) Code Fault/Repair 1-1-1 ……………………….. No Fault 1-1-2 ………………………………………….. Replace ECU 1-1-3 …………………… HO2S Integrator At Maximum Enrichment 1-2-1 ……………………… MAF Sensor Signal Absent Or Faulty 1-2-3 ………… Engine Temperature Sensor Signal Absent Or Faulty 1-3-1 ……………. Ignition System Speed Signal Absent Or Faulty 1-3-2 …………………….. Battery Voltage Too High Or Too Low 2-1-2 …………………….. HO2S Sensor Signal Absent Or Faulty 2-2-1 .. Adaptive HO2S Control, Engine Running Too Rich At Part Load 2-2-3 ………………………. IAC Valve Signal Absent Or Faulty 2-3-1 .. Adaptive HO2S Control, Engine Running Too Lean At Part Load 2-3-2 ……. Adaptive HO2S Control, Provides Richer Mixture At Idle 3-1-1 …………………….. Speedometer Signal Absent Or Faulty 4-1-1 …………………. Throttle Switch Signal Absent Or Faulty 5-1-1 ……. Adaptive HO2S Control, Provides Leaner Mixture At Idle 5-1-2 ……………. HO2S Integrator At Maximum Lean Running Limit (1) - See FUEL INJECTION DIAGNOSIS under DIAGNOSTIC TROUBLE CODE TESTING for fault code diagnosis. TROUBLE CODE DEFINITION - IGNITION SYSTEM (1) Code Fault/Repair 1-1-1 ……………………………………………. No Faults 1-1-2 ………………………………………….. Replace ECU 1-2-3 ….. Engine Temp. Signal From Fuel Injection Absent Or Faulty 1-3-1 …………………………………….. VSS Signal Absent 1-4-3 ………………. Front Knock Sensor Signal Absent Or Faulty 1-4-4 …………. Load Signal From Fuel Injection Absent Or Faulty 1-5-4 ……………………………………. EGR System Leakage 2-1-4 ……………………………….. VSS Signal Intermittent 2-4-1 ……………………………………. EGR Flow Incorrect 3-1-1 …………………….. Speedometer Signal Absent Or Faulty 3-1-4 …………. Camshaft Position Sensor Signal Absent Or Faulty 3-2-4 …………………………… Camshaft Signal Intermittent 4-1-1 .. Throttle Switch Signal From Fuel Injection Absent Or Faulty 4-1-3 ………….. EGR Temperature Sensor Signal Incorrect/Missing 4-3-2 …………………….. High Temperature Warning In ECU Box 4-3-3 ……………….. Rear Knock Sensor Signal Absent Or Faulty 5-1-3 …………………….. High Temperature Warning In ECU Box (1) - See IGNITION SYSTEM DIAGNOSIS under DIAGNOSTIC TROUBLE
CODE TESTING for fault code diagnosis. DIAGNOSTIC UNIT “A” LED DOES NOT FLASH 1) Disconnect diagnostic unit “A”. Turn ignition on. Check for voltage at diagnostic connector terminal No. 4. If voltage is not present, check fuse and wiring. If voltage is present, turn ignition off. 2) Connect an ohmmeter between diagnostic connector socket No. 8 and ground. Ohmmeter should indicate approximately zero ohms. If reading is not approximately zero ohms, check wiring. If wiring is okay, replace diagnostic unit “A”. DIAGNOSTIC UNIT “A” LED FLASHES BUT ECU DOES NOT RESPOND 1) Turn ignition on. Check for voltage at diagnostic socket No. 2 (fuel injection system) or No. 6 (ignition system). Approximately 10 volts should be present. If approximately 10 volts is not present, check wiring. 2) Turn ignition off. Connect Measuring Unit (9813190). See MEASURING UNIT. Connect an ohmmeter between socket No. 2 (fuel injection system) or No. 6 (ignition system) and measuring unit terminal No. 35. If continuity is present, repeat test using a known good ECU. CLEARING CODES 1) Turn ignition on. Press test button for more than 5 seconds. Release button. LED should light after 3 seconds. Press button again for more than 5 seconds. Release button. LED should go out. 2) To ensure codes have been cleared, press button for more than one second (but no more than 3 seconds). If Code 1-1-1 is displayed, codes have been cleared.

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