ECT/VAF Sensor - Harness Repair

REF. NO. 54/76

DATE: May 1996

TO: ALL MERCEDES-BENZ PASSENGER CAR DEALERS

SUBJECT:
ALL MODELS
REPAIRING WIRING HARNESS TO VAF SENSOR (B2) CONNECTOR
AND ECT SENSOR (B11) CONNECTOR





In the event the wiring harness in the area of the volume air flow (VAF) sensor connector or the engine coolant temperature (ECT) sensor connector becomes damaged (e.g. broken wires), the harness can be repaired, thereby avoiding costly replacement of the entire engine wiring harness.

Repair procedure

1. Ignition off! Disconnect harness connector from VAF or ECT sensor and remove harness from harness tray. Remove air filter on vehicles with engine 119.

2. Connect repair connector to VAF and ECT sensor and place attached wiring into harness tray.





3. Cut the individual wires from existing engine harness and the repair connector so that the wire splices can be staggered (arrows, Figure 2). Wire splices must not be next to each other.





Note:
^ When cutting each wire, ensure that it is long enough to allow for a small loop (approx. 1" [25 mm]) at the back of the wire splice(s) (arrow, Figure 3), for strain relief (to prevent the wire from kinking).

^ When cutting wires from the existing engine harness, ensure that they match the color of the wires of the repair connector exactly.





4. Strip approx. 15 mm (1/2") off the ends of the wires (Figure 4).

5. Twist together the wire from the repair connector with the identically colored wire from the existing engine wire harness and insert them into the wire splice (Z, Figure 4). Repeat for each wire.

6. Twist wire splice (Z, Figure 4) completely onto the wires.

Note:
Wire splice (Z) should be used on 18 - 10 gauge (0.75 - 4.0 sq.mm) wire only.





7. Heat wire splice (Z, Figure 5) with hot air gun (approx. 400 °C) starting at ball end until solder ring (1) melts and the sleeve (2) has shrunk neatly around the wires. Do not use flame.





8. Inspect solder connection:
The solder ring (1, Figure 6) should no longer be visible. The sleeve (2) should neatly surround the wires. If the solder ring is not completely melted (partially or fully visible) reheat the wire splice.

9. Cover visible wires with premium quality electrical tape (e.g. 3M Scotch(R) 33) which can withstand a wide temperature range.

10. Install wiring harness into harness tray. Reinstall air filter on engine 119.

11. Connect Hand-Held Tester (HHT), verify VAF or ECT sensor function (actual values), read out faults and erase (refer to Diagnostic Manual Engines Volume 2, Section 0: Connection and Use of Test Equipment).





Parts Information





In Case of Warranty