ARDILLITAS” DE LA CIUDAD DE LOJA, PERIODO 2009-2010

SMCS Code:1129-038-AX

System Operation Description:

Use this procedure under the following situation:

Use this procedure in order to determine if the auxiliary brake circuit is operating properly.

The following background information is related to this procedure:

Auxiliary Brake Operation (Auxiliary Retarder)

The auxiliary brake output circuit is provided by the ECM in order to indicate that conditions are acceptable for an auxiliary brake to operate. Operation of the auxiliary brake output is inhibited during undesirable engine operating conditions. The time period of fueling the engine is an undesirable engine operating condition. The “Auxiliary Brake” parameter must be programmed to J1/P1:12 in order to enable the auxiliary brake output. The output will function on the corresponding output that is selected.

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ECM connector J1/P1:12

In typical applications, the auxiliary brake output circuit operates a relay, which switches battery power in order to energize the auxiliary brake solenoids. An “Engine Brake On” switch will be wired in series with the relay and the “Engine Brake On” switch must be ON before the auxiliary brake will operate.

The ECM does not read the OEM installed Auxiliary Brake Relay Switches in order to determine operation. Only the conditions that are listed below are used to determine operation. The OEM installed auxiliary brake relay switches determine the path of the signal.

In order to ensure the proper operation of the auxiliary brake, the following conditions must be met:

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Engine speed is above 800 rpm.

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The percent of accelerator pedal position is equal to 7 percent or the percent of accelerator pedal position is less than 7 percent.

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The clutch pedal is released.

These conditions must be met regardless of the following parameters:

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Customer Specified Settings for the Engine Retarder

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Auto Retarder in Cruise

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Engine Retarder Minimum Vehicle Speed Additional operating requirements must be met if the “Cruise/Idle On/Off Switch” is in the ON position.

Cruise Control Switch in the ON position

When the cruise control switch is in the ON position, two special options allow the engine retarder to operate only after the driver depresses the service brake pedal. The customer programmable modes of operation are listed below:

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Coast mode

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Latch mode

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Manual mode

The Coast mode engages the engine retarder when the driver depresses the service brake pedal. The retarder disengages when the driver releases the service brake pedal.

The Latch mode engages the retarder when the driver depresses the service brake pedal. The retarder remains engaged until the control detects a change in a control input. Examples of a change in a control input are illustrated on the following list:

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Depressing the accelerator pedal

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Depressing the clutch pedal

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The engine speed drops below 800 rpm.

The third option for the “Engine Retarder Parameter” is Manual mode. In the Manual mode, the retarder operates in the same manner regardless of the position of the cruise control switch. Unlike the Latch mode and the Coast mode, depressing the service brake pedal is not required to initiate the retarder in the Manual mode.

Note:Latch mode and Coast mode determine engine retarder operation only when the cruise control switch is in the ON position. Latch mode and Coast mode do not determine engine retarder operation when the engine is active in cruise control. Latch mode and Coast mode require the initiation of the service brake before acting. The initiation of the service brake disengages cruise control.

The “Auto Retarder in Cruise” parameter does not affect the operation of the auxiliary brake output circuit. The “Auto Retarder in Cruise” parameter is used only when the retarder is connected to the engine wiring harness.

Note:If the “PTO Configuration” is programmed to “Cab Switches”, “Remote Switches”, or “Remote Throttle”, the Auxiliary Brake Output is disabled whenever the PTO On/Off circuit is on. If the vehicle is equipped with an Anti-Lock Brake System (ABS), the vehicle may have an additional relay in the switch circuit for the auxiliary brake solenoids. This is installed so the ABS system can turn off the auxiliary brake solenoids, if necessary. The relay should have normally closed contacts.

The “Engine Retarder Minimum Vehicle Speed” parameter will prevent the operation of the auxiliary brake output below the programmed vehicle speed when vehicle speed is present.

The “Engine Retarder Minimum VSL Type” parameter provides the following two options:

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Hard Limit (default)

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Soft Limit

When the parameter is programmed to the hard limit, the “Engine Retarder Minimum VSL Type” does not allow the auxiliary brake to operate under the following condition:

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The vehicle speed is below the “Engine Retarder Minimum Vehicle Speed”. The “Engine Retarder Minimum Vehicle Speed” is customer programmed.

The soft limit also requires the vehicle speed to be equal to or greater than the programmed “Engine Retarder Minimum Vehicle Speed” in order to initiate the activation of the auxiliary brake, but the soft limit allows the operation of the auxiliary brake to continue below the programmed “Engine Retarder Minimum Vehicle Speed”.

The “Engine Retarder Delay” parameter provides a programmable delay after all of the basic conditions that are required to turn on the auxiliary brake are met. Once the conditions are met the ECM will delay the activation of the auxiliary brake by the programmed additional time. The programmable range is 0 to 3.0 seconds in 0.1 second increments.

g00656152

Illustration 48

Relay circuit for auxiliary brake

g00715816

Illustration 49

Terminal locations for ECM

Test Step 1. Inspect Electrical Connectors

In document UNIVERSIDAD NACIONAL DE LOJA (página 77-81)