Engine Controls - Surge/Intermittent Idle Fluctuations
Classification: EF&EC94-O16Section: Engine Control System
Models: Trucks (D21) with KA24E Engine
Reference: TECHNICAL BULLETIN NTB94-106
Date: November 22, 1994
TRUCK(D21) ENGINE IDLE FLUCTUATION
APPLIED MODEL:
Truck(D21) with KA24E Engine
SERVICE INFORMATION
Some Trucks may exhibit a surge or an intermittent idle fluctuation. The incident may be difficult to diagnose, causing several repair attempts to be made. Such incidents may be caused by a poor electrical connection at a splice joint where the ground wire (B/G) from the E.C.M. meets three other wires from the Engine Coolant Temperature Sensor, Exhaust Gas Recirculation Temperature Sensor and the Throttle Position Switch. If the splice joint connection is poor, the ground for these sensors is intermittently interrupted, causing improper E.C.M. input readings. The incident may be induced or alleviated by moving the engine/injector harness by hand as shown (Figure 1).
SERVICE PROCEDURE
1. Remove air cleaner assembly and detach engine harness from engine (section between valve cover and throttle body). (Figure 2)
2. Remove the harness covering (plastic shield/electrical tape) and locate the splice connection. A single ground wire (B/G) is connected to three other wires (also, B/G) with a pressed metal connector.
To ensure a positive connection at this splice, solder the metal connector to the wires to form a permanent connection (Figure 3).
3. Wrap soldered splice with heat shrink tape to ensure a waterproof seal. Reinstall plastic shield and wrap with 3M Electrical Tape (3M P/N 88) or equivalent.
4. Reattach harness to engine and replace air cleaner assembly.
5. Test drive vehicle to ensure that incident is resolved.
WARRANTY INFORMATION