Wiring Information - B5 1.8T

[Grant620]

Hi Guys,
Can anyone assist with a technical question about ECU wiring on an Audi A4 B5 1.8T (99 MY)
On the ECU there are two wires that I don't seem to be able to work out the function of:
Pin 5 - Green / Black
Pin 18 - Yellow
Also, on the Instrument Cluster, blue plug, Pin 16 is meant to be the MIL / CEL Light, but the loom is empty at the connector. Does the CEL light get a signal from a different wire?

Any help would be massively appreciated.

[FrenchAudi]

According to diagrams in my Bentley manual.
Pin 5 (gn/bk) goes to pin 35 on the TCM (Transmission control module)
Pin 18 (y) is noted as being for ACS and Trip Computer only, and goes to T10y/1 (Wire connector, 10 point, blue, connector station, electronics box in plenum chamber.
and T20/1 on J189 (ACS and Trip Computer only). J189 is identified on another diagram as Auto Check System.

T32 - Wire Connector, 32 Point, blue, which I think is the plug you refer to on the Instrument Cluster, has a yellow/brown on Pin 16 (which goes to K18 - Trailer Operation Indicator Light). The y/br wire is from track number 51, which shows it connected to Pin 17 on J220, the Motronic ECM.

I hope this is of some help. I find these diagrams I have very confusing, covering so many different versions of the A4 in only 6 years with 2 different engines.

It's easy to see why CAN bus became essential!

[Grant620]

Thanks for that.
Interesting... So any idea what the ECU puts out on Pin 18?

I don't have any wires on Pin 17 of the J220.

[FrenchAudi]

Thanks for that.
Interesting... So any idea what the ECU puts out on Pin 18?


Sorry, I don't know. The book diagram only shows where the wires go, not what's inside the magic boxes.

[arman123]

found this online for instrument cluster






Pin assignment at multi-pin connectors on instrument cluster - vehicles from model year 1998











Multi-pin connector, 32-pin, blue




1 -
Terminal 15




2 -
Turn signal (right-side)




3 -
Speedometer output 1




4 -
Not used




5 -
Fuel gauge sender




6 -
Airbag




7 -
Terminal 31 (sensor earth)




8 -
Coolant temperature




9 -
Terminal 31 (load earth)




10 -
Oil pressure switch




11 -
Engine speed signal




12 -
Terminal 61




13 -
Glow period warning lamp or CAT




14 -
Self-levelling suspension




15 -
Terminal 58d




16 -
Trailer turn signal / fault in engine electrical system




17 -
Main beams




18 -
Turn signal (left-side)




19 -
ABS




20 -
Terminal 58s




21 -
Door contact, driver's side




22 -
Coolant level low




23 -
Terminal 30




24 -
Terminal 31 (load earth)




25 -
K wire




26 -
Right parking light




27 -
Left parking light




28 -
Speedometer input




29 -
Brake fluid level/pressure




30 -
S contact




31 -
Belt buckle




32 -
ESP




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