Activating FACTORY switches / adding switch

Paccar ESA, dealer has the program and can do everything properly.

 

What model truck and engine. B cabs are way easier than the 2.1M NGP cabs.

 

That truck should already be wired for the fan, and fog lights. You just have to add the lights and switch. The fan may just need the switch.

The back up alarm will be a little more in depth, but somewhat simple. You should be able to simply interrupt the power or ground to the alarm. This could be done by cutting the wire at the alarm end, now splice a wire to each cut end I would use 12ga. You will need to run the 2 wires all the into the cab, and wire them to a on/off. There is a rubber grommet behind the filler panel under both side mirrors to pass the wires through.

 

Thought harnesses on 2.1 cabs used basic harness and have to add overlay harnesses to it. The B cab 1.9M have all the connections and wires already in the harnesses so adding features is easy. From 2.1 cab service manual:

Harness Design and Assembly


Introduction

The main cab harness in 2.1 meter width cabs are

designed and assembled differently than the 2.3 or

1.9 meter width cabs. Instead of a main harness

with full content and terminated connectors for

the options, the harness will only have wires for

the options ordered when new and will have a

very limited number of terminated connectors.

Any optional terminated connectors will be on the

harness as a customer furnished option specified

on the sales order.

The newly designed harness receives sales codes

as input and generates a part number generator

for production. The harness has a 'base' for all

standard content. The harness diagram then

specifies different 'layers' that production will

'overlay' onto the base harness. Once all the

layers are installed, production will install the

pins into the connectors and wrap up the wires

into the final harness. Hence, this concept has

been commonly referred to as the 'base overlay

harness'.

On the harness drawing the layers are

documented in a series of reference tables. Each

option adds electrical content to the harness,

which, in turn creates a chassis unique harness. .

Base overlay eliminates many unnecessary in-line

connectors for optional equipment, and reduces

the opportunities for loose connections in an

electrical system

This results in:

• better routing

• fewer points of failure

• easier troubleshooting

• fewer unused connectors

How to Read Base Overlay Diagrams

1. Identify the part numbers that were installed

at the factory (authorized dealers and their

agents will use Web ECAT).

2. Interpret/decode the layers installed by using

the variables of the part number broken down

on the diagram.

3. Look up the layer in the same diagram (later

sheets) to identify the circuits, pins etc that

involve the option layer.

4. Refer to the diagram sheet that displays the

schematic of the overlay (typically shown as

a dashed line) which will help identify how

the layer is physically located relative to the

harness itself.

5. Follow the circuit to the pin locations to aid in

diagnosis.

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