Hardbody
Harness Headaches
Does
this conversation sound familiar? "How's that Nissan truck with the idle
fluctuation problem coming?" the service writer asks. "The owner has called
three times, wondering what we've found." The frustrated technician replies,
"The problem is hard to pin-point because it's so inconsistent. I've connected
the scan tool and investigated all the diagnostic trouble codes it gave
me. The components and circuits all seem good. I just don't know what
else to check." Well my friends, have I got a tech tip for you. Some 1990
to 1995 Nissan Trucks with a KA24E engine may exhibit a surge or an intermittent
idle fluctuation. The incident may be difficult to diagnose because it
may be caused by a poor electrical connection at a splice joint where
the ground wire (B/G) from the Engine Control Module (ECM) meets three
other wires from the Engine Coolant Temperature Sensor, EGR Temperature
Sensor and the Throttle Position Switch. If the splice joint connection
is poor, the ground for these sensors can be intermittently interrupted,
causing improper ECM input readings.
If
you find the incident may be induced or alleviated by moving the engine/injector
harness by hand as shown in Figure 1, the following procedure relates
how to repair this problem.
1. Remove air cleaner
assembly and detach the engine harness from the engine (section between
valve cover and throttle body) as shown in 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.
3. To ensure a positive
connection at this splice, solder the metal connector to the wires to
form a permanent connection (Figure 3).
4.
Wrap soldered splice with heat shrink tape to ensure a waterproof seal.
Reinstall plastic shield and wrap with high quality electrical tape.
5. Reattach harness to the engine and replace the air cleaner assembly.
Clear any diagnostic trouble codes you may have had and test-drive the
vehicle to make sure the problem's resolved.
You should be able to make the repairs in less than an hour and don't
forget to charge for your diagnostic time.
You've definitely earned it!
©
2000 ALLDATA LLC
