diagram AUDI A8 1995 D2 / 1.G AHA Engine On Board Diagnostic Workshop Manual

01-3

Checking function

- Switch ignition on.

MIL must light up.

- If MIL does not light when ignition is switched
on, check wiring to MIL as follows: Cause:
MIL is not triggered, or does not light,
due to faulty wiring or open circuit. Remedy:
- Switch ignition off.
- Connect VAG1598/22 test box.
- Connect jumper wire to bridge test box sockets 2 and 17.
- Switch ignition on.
MIL must light up.
If MIL does not light:
- Switch ignition off.
- Check bulb for MIL.
If bulb is OK:
- Check wiring for open circuit between MIL and Motronic ECM -J220- using
applicable wiring diagram.
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01-4
If MIL lights up when ignition is switched on,
continue checking as follows:

- Start engine and let run at idle.

MIL must go out after a few seconds.
If MIL does not go out:

- Check Diagnostic Trouble Code (DTC) memory
page 01
-16
.
If there are no malfunctions stored in DTC
memory: Cause:
MIL is triggered continuously due to
short circuit to Ground. Remedy:
- Switch ignition off.
- Connect VAG1598/22 test box.
- Check resistance between test box socket 17 and vehicle Ground, specified value:
(no continuity) If the specified value is not obtained:
- Check for short circuit to Ground in wiring from Motronic Engine Control Module
(ECM) -J220- to MIL.
- Trace malfunction using applicable wiring diagram and repair as necessary.
If there is no continuity, and no short circuit to Ground:
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Battery Positive Voltage (B+) OK (at least 11
volts)
Engine and transmission GND connections
OK Electrical Wiring Diagrams,
Troubleshooting & Component Locations
binder

Fuel pump relay OK
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01-64

Display field 3
Possible malfunction cause
Corrective action
less than 62
(all-wheel drive)
or
less than 74
(front-wheel drive)
Drive range selected
Throttle valve control module faulty- Move selector lever to "P" or "N" position
- Check idle speed page 24
-16
- Check throttle valve control module page 24
-128

less than 74
(front-wheel drive)
Supply voltage (terminal 15) to terminal 10
of Engine Control Module (ECM) missing - Check supply voltage (terminal 15) to terminal
10 of ECM using applicable wiring diagram
greater than 74
(all-wheel drive)
or
greater less than 86
(front-wheel drive) Closed Throttle Position (CTP) switch open
Throttle valve control module faulty
Intake air leaks ("false air")- Check idle speed page 24
-16
- Check throttle valve control module page 24
-128

- Check intake air system for leaks page 24
-
126

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