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XK8 |
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DATE 9/98 |
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501-11 |
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Amended 1/99 |
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SERVICE |
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TECHNICAL BULLETIN |
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Convertible Top Electrical System –
Component Descriptions & Diagnosis
MODEL 1997 MY-ON
XK8 Convertible
VIN
001001-ON
Remove and destroy Bulletin 501-11, dated 9/98. Replace with this Bulletin.
A description of the convertible top system
opening and closing sequence has been added.
Issue:
This Technical Bulletin provides information which should enable the diagnosis and repair of possible malfunctions within the electrical components of the power convertible top system. Mechanical failures are not covered in this Technical Bulletin.
Action:
Refer to section below for component descriptions. Refer to page 5 for fault diagnosis. Refer to Fig. 15.2 of the XK8 Electrical Guide for an electrical schematic of the convertible top system.
COMPONENT DESCRIPTIONS
Hydraulic Pump
Located in the right side of the luggage compartment. The pump can be operated in two directions depending on the required direction of the convertible top (push direction - pistons extend, pull direction - pistons retract). There is a separate fluid outlet for each direction since the fluid returns through the other outlet which then functions as an inlet.
Convertible Top Hydraulic Cylinders
Located on each side of the rear seat, they are attached between the body and the convertible top frame. When hydraulic fluid is pumped into the base of the cylinders the pistons extend, raising the convertible top. Fluid directed to the top of the cylinders cause the pistons to retract, lowering the convertible top.
Latch Mechanism Hydraulic Cylinder
Located above the windshield in the latch plate assembly, the cylinder controls the convertible top latching mechanism which basically comprises a claw and two locking pins. The cylinder, either locks or releases the latching mechanism. At the end of the convertible top closing cycle, the claw engages the convertible top and pulls it into the latch position, where the locking pins secure the convertible top in place. On receiving a request for the convertible top to be opened, the cylinder retracts the two locking pins and opens the claw, releasing the convertible top, allowing the convertible top cylinders to take over the convertible top opening cycle.
Date of issue 9/98 Amended 1/99 |
Bulletin Number 501-11 Page 1 of 10 |
Hydraulic Pump Control Relays
The relays are located in the luggage compartment fuse box.
When the Top Up Relay is energized, the hydraulic pump is in convertible top raising mode (push direction - pistons extend).
When the Top Down Relay is energized, the hydraulic pump is in convertible top lowering mode (pull direction - pistons retract).
The two relays are controlled directly by the Security and Locking Module (SLCM) located below the fuse box in the luggage compartment.
Hydraulic Control Solenoid Valves (Latch Control Valve and Main Control Valve)
Located on top of the convertible top’s hydraulic pump, the solenoids are identified by colored dots: Latch Control Valve = Blue, Main Control Valve = Orange.
Both solenoids are controlled by the Security and Locking Control Module (SLCM) which is located below the luggage compartment fuse box. The solenoids control the flow of fluid to and from the base of the hydraulic cylinders:
When energized, the Latch Control Valve allows fluid to be pumped into the base of the latch mechanism cylinder to extend the piston. When de-energized, the Latch Control Valve allows fluid to exit the base of the latch mechanism cylinder to allow the piston to retract.
When energized, the Main Control Valve allows fluid to be pumped into the base of the convertible top cylinders to extend the pistons. When de-energized, the Main Control Valve allows fluid to exit the base of the convertible top cylinders to allow the pistons to retract.
Convertible Top Switch
The switch is located in the center console in front of the radio.
When the switch is pressed it signals to the Body Processor Module (BPM) to either open or close the convertible top. The BPM communicates the request via the SCP - BUS to the SLCM for as long as the switch is held in the respective position.
There are five microswitches in total which inform the SLCM of the convertible top’s position: The “Top Ready To Latch” Switch, “Top Latch Closed” Switch, and “Top Closed” Switch are located in the latch mechanism, and are connected to the BPM which is located behind the glove compartment.
The “Top Down” Switch is located on the bottom of the right side convertible top cylinder and is connected to the SLCM.
The “Top Raised” Switch is located on top of the right side convertible top cylinder and is wired in series with the “Top Ready To Latch” Switch.
The BPM notifies the SLCM of any change to the “Top Ready To Latch” Switch, the “Top Latch Closed” Switch, or the “Top Closed” Switch via the vehicle SCP - BUS.
The functions of the microswitches are given in more detail in the section Operation of Microswitches.
Page 2 of 10 Bulletin Number 501-11 |
Date of issue 9/98 Amended 1/99 |
OPERATION OF MICROSWITCHES
Overview
“Top Ready to Latch” Switch and “Top Raised” Switch
When both of these switches are closed, the system signals that the convertible top is over center, and that the top has contacted the latch claw.
“Top Closed” Switch
When this switch is closed, the system signals that the top has been successfully grabbed by the latch claw.
“Top Latch Closed” Switch
When this switch is closed, the system signals that the latch has retracted successfully, and that the locking pins are extended.
“Top Down” Switch
When this switch is closed, the system signals that the top is completely open.
Description
When the Security and Locking Control Module (SLCM) receives a convertible top action request from the main control switch, the SLCM monitors each mechanical movement via the microswitches as the convertible top cycles through its open or close operation. The microswitches signal when the cylinders and latch mechanisms have completed each of their designated operations.
“Top Ready To Latch” Switch: Latch Claw.
•When the claw is fully raised (open) the “Top Ready To Latch” Switch is ‘open circuit’.
•When the claw is in the lowered position (closed) the “Top Ready To Latch” Switch is ‘closed circuit’.
•On a convertible top closing cycle, the SLCM waits until the “Top Ready To Latch” Switch and the “Top Raised” Switch are ‘closed circuit’ before it triggers the latch pins to close.
•On a convertible top opening cycle, the SLCM is informed that the convertible top has left the claw when the “Top Ready To Latch” Switch switches to ‘open circuit’.
Note: The “Top Ready To Latch” Switch is wired in series with the “Top Raised” Switch therefore, both switches must be closed before the BPM input is grounded.
“Top Closed” Switch: Latch Claw.
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The “Top Closed” Switch informs the SLCM of the position of the convertible top. |
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Before the claw lowers the convertible top into latch position, the “Top Closed” Switch is |
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‘open circuit’. |
•When the claw has lowered the convertible top into latch position, the “Top Closed” Switch switches to ‘closed circuit’.
•On a convertible top opening cycle, the SLCM begins to power the convertible top cylinders when the “Top Closed” Switch switches to ‘open circuit’.
Date of issue 9/98 Amended 1/99 |
Bulletin Number 501-11 Page 3 of 10 |
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