Replace the Internal Harness Assembly on ALLISON Transmission 4700 OFS

Control Harness Assembly - 29549576

Internal Harness Allison Transmission 

Figure 1.1 - Control Module (4700 OFS)

A). Drain Fluid

→Drain the Transmission fluid. The Transmission fluid should be warm to promote complete drainage.

→Remove the drain plug from the Control Module.

→Disconnect all hydraulic hoses from the Transmission.

B). Disconnecting the Transmission external harness 

→Loosen bolt in 20-way Transmission feedthrough harness connector.

→Disconnect the Transmission external harness from the 20-way Transmission feedthrough harness connector.

Figure 1.2 - Feedthrough Connector (20-way)

C). Removal of Control Valve Module

→Remove forty-three bolts and retaining Control Module to the main housing module, including the bolts retaining the filter covers.

→Loosen Control Module by applying pressure at the reinforced tabs or use jack bolts, inserted into the Control Module bolt holes that bottom against the main housing module.

Figure 1.3 - Main Housing Module

→Remove covers and filters if a handhold is needed to remove the Control Module.

→Remove Control Module assembly and gasket.

Figure 1.4 - Control Module Removal

WARNING: Get help when lifting the Control Module. Assistance from another person may be required. The control module weighs approximately 25 kg (55 lb).

D). Removal of Electrical Components and Sensors

→Disconnect all connectors. Release connectors in the wire harness by pushing in the center tab with a small screwdriver.

→Remove three bolts from standoff assembly.

→Remove standoff assembly.

Figure 1.5 - Standoff assembly

E). Measuring Resistance
→Measure resistance of each solenoid (must be 4–8 ohms).
→Inspect Diagnostic Pressure Switch (PS1). Maximum resistance of pressure switch must not exceed 2 ohms. Minimum resistance of pressure switch (open) must be at least 20.000 ohms. The switch should close between 159–255 kPa (23–37 psi).

Figure 1.6 - Measuring Resistance

→Inspect Transmission Fluid Temperature (TFT) Sensor. 

→Inspect and clean the Oil Level Sensor (OLS) with a soft cloth.

F). Installation of new Electrical Components and Sensors (refer to Figure 1.1 above) 

→Position wire harness assembly (Allison P/N 29549576) onto Control Valve Module.

→Install wire harness assembly. Secure standoff assembly with three bolts. Connect all connectors. Tighten bolts to 5–8 Nm (4–6 lb in).

→Install new Case Gasket (Allison P/N 29501099). 

G). Installation of Control Module

→Install two guide pins in two main housing bolt holes.

→Lubricate the feedthrough hole in the main housing with oil-soluble grease.

→Guide Control Module onto the main housing and pass feedthrough harness connector through the feedthrough hole in the main housing.

→Align the Control Module bolt holes with the guide pins. Make sure the feedthrough harness standoff is aligned with the feedthrough hole in the main housing.

→Lower the Control Module over the guide pins until it seats against the main housing.

→Install filter cover assemblies.

→Install the remaining bolts and tighten them to 51–61 Nm (38–45 lb ft).

Figure 1.7 - Control Module Installation

H). Refill Transmission

→Inspect the drain plug. Replace the O-ring. Install the drain plug and tighten it to 25–32 Nm (18–25 lb ft).

→Connect all hydraulic hoses.

→After refill, determine if fluid level is correct.

Read More:

ALLISON Transmission Solenoids 3000/4000 Series

ALLISON Transmission Solenoids 5000/6000 Series

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