Technical factory head unit pin voltages

[arekp]

wonder if anyone knows which pin has the reverse camera trigger input, or is it through canbus?

it must be through pins 1-20, but the voltages I get are the same in neutral and in reverse:
pin 1: empty/blank
pin 2: 3.2V
pin 3: empty/blank
pin 4: empty/blank
pin 5: 2.6V
pin 6: 0V
pin 7: 0V
pin 8: empty/blank
pin 9: empty/blank
pin 10: empty/blank
pin 11: empty/blank
pin 12: empty/blank
pin 13: 0V
pin 14: 0V
pin 15: 0V
pin 16: 2.4V
pin 17: empty/blank
pin 18: empty/blank
pin 19: 1.9V
pin 20: empty/blank

for ground, I've tried pins 33 (reverse camera ground) and 43 (main ground on harness) , but outcome is the same

 

[s130]

The rear view camera (RVC) communicates with the BCM via LIN2

There are 4 LIN coms link on the Body Computer.

https://en.wikipedia.org/wiki/Local_Interconnect_Network

LIN (Local Interconnect Network) is a serial network protocol used for communication between components in vehicles. It is a single wire, serial network protocol that supports communications up to 19.2 Kbit/s at a bus length of 40 meters. The need for a cheap serial network arose as the technologies and the facilities implemented in the car grew, while the CAN bus was too expensive to implement for every component in the car. European car manufacturers started using different serial communication technologies, which led to compatibility problems.

Pinouts for the 5" and 6.5" Head Units

Sorry about the ordering but you can copy and paste then re-order if you want for clarity.

PIN Function
1 Can C1 H
28 N.C.
2 BH CAN H
29 Microphone 1 -
3 N.C.
30 Microphone 1 +
4 N.C.
31 Rear camera signal +
5 BH CAN H
32 Rear camera signal -
6 Audio_1 / Aux_In_right
33 Rear camera signal shielding
7 Audio_1 / Aux_In_ detection
34 N.C.
8 Audio_2 / RSE CD right
35 N.C.
9 Audio_2 / RSE CD detection
36 N.C.
10 Audio_2 / RSE CD left
37 N.C.
11 Can C1 L
38 N.C.
12 BH CAN L
39 N.C.
13 Backlighting for Media Hub
40 N.C.
14 N.C.
41 N.C.
15 BH CAN L
42 N.C.
16 Audio_1 / Aux_In_left
43 Earth
17 Audio_1 / Aux_In_Detection
44 +30
18 Audio_1 / Aux_In_Shielding
45 Rear right +
19 Audio_2 / RSE CD Shielding
46 Front right -
20 N.C.
47 Front left +
21 N.C.
48 Rear left +
22 N.C.
49 Rear right -
23 N.C.
50 Front right +
24 N.C.
51 Front left -
25 N.C.
52 Rear left -

 

[arekp]

thanks @s130, with multimeter I confirmed:
pin 31 was signal +
pin 32 was return -
pin 33 was shield

there is no individual line as the reverse trigger (like older cars have) but instead it all happens via the can bus

I added a cable to my after market head unit connector which was missing inputs at pins 31 & 32, adjusted some settings, and voila!

I've done a DIY guide on how to install an android head unit and retain the factory reverse camera input

And yes, the lines adjust as you turn steering wheel

 

[s130]

So you are saying that you have the CAN BUS trigger and control all working OK now?

Good for you. The info I posted re: LIN (Local Interface Network) data back to 2015 ish so no doubt Fiat have updated the technical info for later models.

 

[arekp]

yes, can bus trigger & control working for reverse, phone, volume, track, cruise control