1988 Audi 80 Base, AutomaticFACTORY OEM SERVICE PROCEDURE

Starting Enrichment

  1. Ensure engine is at normal operating temperature and no fault codes are stored in ECU memory. Using a digital multimeter and Harness Adapter (VW1315A/1 ), check voltage at differential pressure regulator.
  2. Connect multimeter to differential pressure regulator. See Fig 1 . Remove fuse No. 13 and remove and ground ignition coil wire. Crank engine and observe volt reading. Control voltage should drop to 35-45 mA, during engine cranking, and remain there for a maximum of 3 seconds. After 3 seconds, voltage should drop to zero.
    Fig 1: Checking Starting Enrichment
    G94368Courtesy of AUDI OF AMERICA, INC.
  3. With multimeter still connected and ignition off, disconnect O2 sensor and CTS harness connectors. Connect Adjustable Resistance Box (VW1630 ) leads to CTS harness connectors. Set resistance to 2500 ohms. Install ignition coil wire and start engine. Control voltage should read 15-23mA in about 6-9 seconds, then slowly drop to 9-11 mA.
  4. Move throttle quickly to full throttle and release throttle. Control voltage must increase briefly to 6 mA. If system fails test, perform electrical tests. See CIS-MOTRONIC VOLTAGE & RESISTANCE TESTS  chart. See Fig 2 . If system electrical tests are okay, replace ECU. Clear fault codes.
Fig 2: CIS Motronic Harness Connector.
G94369Courtesy of AUDI OF AMERICA, INC.
CIS-MOTRONIC VOLTAGE & RESISTANCE TESTS

Test Step No. Connection Terminals Test Specifications
1 14 & 35 Ignition "ON"; About Battery Voltage
2 17 & 35 Ignition "ON"; About Battery Voltage
3 32 & 35 Ignition & A/C "ON"; About Battery Voltage
4 33 & 35 Ignition & A/C "ON"; About 1V Below Battery Voltage
5 19 & 35 Ignition "ON"; About Battery Voltage
6 (1) 13 & 35 Insert Fuel Relay Fuse; FIL Must Light
" " Ignition "ON"; FIL Must Light
7 4 & 5 Ignition "OFF"; 15-25 Ohms
8 3 & 35 Ignition "OFF"; 2500 Ohms @ 68°F (20°C)
" " Ignition "OFF"; 200 Ohms @ 212°F (100°C)
9 31 & 35 Throttle Closed; Open (No Continuity)
" " Throttle Wide Open; Continuity
10 28 & 35 Throttle Closed & Open; Continuity
11 (2) 28 & 35 Continuity
12 13 & 35 Insert Fuel Relay Fuse; Continuity
13 14 & 16 About 10 Ohms
14 14 & 15 30-60 Ohms
15 . Unplug Hall Effect Sensor Connector
15 30 & 35 Terminals 1 & 2 To HallEffect Sensor; Continuity
15 30 & 21 Terminals 2 & 3 To HallEffect Sensor; Continuity
16 11 & 35 Remove Terminal From Coil. Power Output Stage Of Ground Center Contact; Continuity
17 " Disconnect KS Harness Connector; Open (No Continuity)
6 & 8 Connect Terminals 1 & 2; Continuity
" " Connect Terminals 1 & 3; Continuity
18 7 & 35 Disconnect O2 Connector& Ground; Continuity
19 23 & 26 Sensor Plate In Rest Position; About 5000 Ohms
20 26 & 35 Sensor Plate In Rest Position; About 4000 Ohms
21 34 & 35 Standard Transmission; Continuity
" " Automatic Transmission Open In "P" or "N"; No Continuity
22 12 & 35 Remove Fuel Pump Relay And Ground Terminal No. 47 Of Fuse Panel Relay
(1) Calif. only.
(2) Non-Calif. only.
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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.