I’ve got the electrical diagram of the instrument cluster and I’m looking to tap two leads to control my Pioneer AVIC-D3 DVD/Radio/CD/Nav/BackupCam. So here is my question on the diagram below: What do the terminals
A21 DIM LED, A30 CAN WAKE UP, A31CAN HIGH DISPLAY, A32 DIM LAMP
mean?
I'm looking to connect the AVIC wake up lead (to start the device) and another to dim. The only two circuits in the car that will do what I want are in the instrument cluster (LED displays & photosensitive cluster backround). Any and all takers welcome to conjure up a guess??
Thanks,
- Stevie
Can high and Can low are the two CAN networks that run in the car, HIGH transfers information for the important functions like PASM, PSM, etc. Low controls comfort, convenience features and there is some redundancy between the two. The CAN control center actually is in the instrument cluster in the Cayman. I don't think you'll be able to tap those.
That's all I know... the dim leads might be connected to be the light sensor, and are probably typical electric lines.
suneet, I am not sure that the CAN processor is on the cluster. Remember the cluster is only displaying stuff like engine/wheel speed, sensor status like heat, oil, water, fuel and the computer that displays mpg, est. fuel, trip odometer, warning sensors and has no fiber optic connections. The cluster displays are activated by CAN but has no other engine/vehicle management control. Perhaps
A30 CAN WAKEUP
activates the LEDs when you open the door? If so then, this leads me to wonder if either
A20 DIM LAMP
and
A21 DIM LED
illuminate the gauges in low light condition? -Stevie
You're right... as of MY05 the Gateway unit is separate from the instrument cluster.
Anyways, the CAN bus incorporate several control units and has a series of digital and analog inputs and outputs. I know for sure that inside lights, light swiches, the dash illumination potentiator are all analog signals on the Cayenne... as I've seen the CAN diagrams for the Cayenne; they're in the file that I link to later. I would image those are the same for the Cayman.
However, the CAN display high and can display low, I'm pretty certain, are the digital leads that transfer the data to the gauge display (audio, nav, trip computer, etc.). You see the same cables on the CAN plug on the back of the headunit... as it's a part of the network.
This file
shows in theory how the CAN bus works, page 1.10 shows the network map on the 987/997. It shows the CAN display network has its own gateway controller, and connects to the instrument cluster, PCM2.1 and the sport chrono. Can Drive on the map is the "high" priority network, the CAN Comfort is the "low" priority networks; that's explained in the subsequent pages.
Thanks for the good information, Suneet. It was helpful in understanding the diff between CAN and MOST and, I learned that CAN signals travel over copper (and MOST over fiber). This means the CAN leads will not provide sufficient nor consistent voltage to satisfy the AVIC control switch. This leaves only two leads that I suspect may achieve my objectives;
A20 DIM LAMP
and
A21 DIM LED
.
Now, looking closer at the circuit in the diagram that connects to
A21 DIM LED
, they all go to other LED lights (air vents, central button module, etc.). Do you know off hand if they automatically dim in low light condition? If yes, then I’ve got my dim control. I can't check until I get the Cayman back in the garage tonight. -Stevie
