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1995 ENGINE PERFORMANCE Volvo - Self-Diagnostics
850
INTRODUCTION
If no faults were found while performing procedures in the F - BASIC TESTING article, proceed with self-diagnostics. 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 SYSTEM
RETRIEVING CODES
CAUTION: Self-diagnostics for fuel injection and ignition systems are separate. Use proper information for system being diagnosed.
Fuel Injection & Ignition Systems
Each system features a self-diagnostic function for fault tracing. Codes are retrieved using diagnostic unit "A" located in engine compartment, in front of right strut tower. Diagnostic unit "A" is equipped with an LED indicator, activation button and function selector cable. See Fig. 1.
NOTE: Diagnostic unit "B" is not used for engine performance applications.
Diagnostic unit "A" output socket No. 2 is used for fuel injection diagnosis, and socket No. 6 is used for ignition system
GLYPH<3> G - TESTS W/CODES
GLYPH<3> 1995 Volvo 850
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
| Code 1-1-1 1-1-2 1-1-3 1-2-1 1-2-3 1-3-1 1-3-2 2-1-2 2-2-1 2-2-3 2-3-1 2-3-2 3-1-1 4-1-1 5-1-1 5-1-2 | Fault/Repair ..................................................... No Fault .................................................. Replace ECU ........................ HO2S Integrator At Maximum Enrichment ........................... MAF Sensor Signal Absent Or Faulty ............ Engine Temperature Sensor Signal Absent Or Faulty ................ Ignition System Speed Signal Absent Or Faulty .......................... Battery Voltage Too High Or Too Low .......................... HO2S Sensor Signal Absent Or Faulty .. Adaptive HO2S Control, Engine Running Too Rich At Part Load ............................ IAC Valve Signal Absent Or Faulty .. Adaptive HO2S Control, Engine Running Too Lean At Part Load ....... Adaptive HO2S Control, Provides Richer Mixture At Idle .......................... Speedometer Signal Absent Or Faulty ...................... Throttle Switch Signal Absent Or Faulty ....... Adaptive HO2S Control, Provides Leaner Mixture At Idle ................ HO2S Integrator At Maximum Lean Running Limit |
|---|---|
| (1) | - See FUEL INJECTION DIAGNOSIS under DIAGNOSTIC TROUBLE CODE TESTING for fault code diagnosis. /a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0 |
Table Caption: This table lists diagnostic trouble codes and their corresponding fault descriptions and repair actions.
TROUBLE CODE DEFINITION - FUEL INJECTION SYSTEM (1) /a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0
TROUBLE CODE DEFINITION - IGNITION SYSTEM (1) /a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0✁/a0
| Code | Fault/Repair |
|---|---|
| 1-1-1 1-1-2 1-2-3 1-3-1 1-4-3 1-4-4 1-5-4 2-1-4 2-4-1 | .................................................... No Faults .................................................. Replace ECU ..... Engine Temp. Signal From Fuel Injection Absent Or Faulty ............................................ VSS Signal Absent ................... Front Knock Sensor Signal Absent Or Faulty ............. Load Signal From Fuel Injection Absent Or Faulty ........................................... EGR System Leakage ...................................... VSS Signal Intermittent ........................................... EGR Flow Incorrect |
| 3-2-4 4-1-1 4-1-3 4-3-2 4-3-3 | .......................... Speedometer Signal Absent Or Faulty ............. Camshaft Position Sensor Signal Absent Or Faulty ................................. Camshaft Signal .. Throttle Switch Signal From Fuel Injection Absent Or .............. EGR Temperature Sensor Signal .......................... High Temperature Warning In ECU |
| Rear Knock Sensor Signal Absent Or | |
| 3-1-1 3-1-4 | |
| Intermittent Faulty | |
| Incorrect/Missing Box | |
| .................... Faulty .......................... | |
| 5-1-3 | High Temperature Warning In ECU Box |
Table Caption: This table lists diagnostic trouble codes (DTCs) and their corresponding faults or required repairs, categorized by code ranges.
CODE
