Technical Body computer pinout here

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Technical Body computer pinout here

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Here are the functions and pinout on the Punto Mk2 body computer (petrol model) that may be of use to others:

Body computer functions include:

Receiving control signals from switches
Activating indicators, courtesy lamps, etc.
Acquiring, converting and transmitting signals to the CAN-bus (ABS, fuel level, etc.)
Managing fault diagnosis of the connectors involved and transmitting to the CAN-bus
Control of exterior lighting via semiconductors or relays
Function checks - faults signalled to instrument panel via CAN-bus


Body Computer connector A

1 Left hand door open switch
2 Left side indicator repeater lamp
3 Right rear indicator lamp
4 Fuel level sensor (+)
5 Left tail lamp
6 Right tail lamp
7 Alarm sensor serial line
8 Left front door lock - open signal
9 Not connected
10 Autoclose serial line (may be for electric windows)
11 Right hand door open switch
12 Left rear indicator lamp
13 Right side indicator repeater lamp
14 Handbrake "on" switch
15 Fuel level sensor (-)
16 Left rear door lock - open signal
17 Right front door lock - release signal
18 K-line aggregate 3
19 Not connected
20 Not connected
21 Courtesy lamp timer control
22 Right hand brake lamp
23 Courtesy lamp supply
24 Left front door lock - release signal
25 Right front door lock - open signal
26 Left rear door lock - open signal
27 Alarm sensor supply
28 Not connected
29 Not connected
30 Not connected
31 Left rear fog lamp
32 Left hand brake lamp
33 Boot lamp supply
34 Left front door lock - locking signal
35 Right front door lock - locking signal
36 Boot open switch
37 Not connected
38 Not connected
39 Not connected
40 Not connected


Body Computer connector B (EOBD socket)

1 K-line ABS control unit
2 Not connected (standardUS)
3 K-line Air bag control unit
4 Power earth
5 Signal earth
6 CAN-bus B
7 K-line engine ECU, auto-transmission
8 K-line immobilizer
9 Preparation for aggregates 1 (dashboard)
10 Not connected (standardUS)
11 Anti-theft device (alarm)
12 Preparation for aggregates 2 (front)
13 Preparation for aggregates 3 (rear)
14 CAN-bus A
15 Not connected (L-line)
16 Supply


Body Computer connector C

1 Reversing signal for steering column switch
2 Not connected
3 Screen
4 Immobiliser CODE aerial
5 Immobiliser CODE aerial
6 ABS serial line
7 Speedometer signal from ABS
8 Front fog lamps relay R14
9 Main beam relay R2
10 INT supply for speedometer generator
11 Not connected
12 Not connected
13 Headlamp washer switch on column
14 Headlamp washer relay R17
15 Earth for speedometer generator
16 K-line for ABS
17 Speedometer signal from pulse generator
18 Brake fluid level sensor
19 Alternator +D signal
20 K-line for ECU diagnostics
21 RF aerial earth (another source states pin C3)
22 Not connected
23 Not connected
24 Bonnet open switch
25 Alarm siren serial line
26 CAN-bus A for electric steering
27 CAN-bus B for electric steering
28 Repeater for speedometer signal
29 ISO5 interface - immobiliser and ECU
30 Right front sidelight
31 RF aerial (another source states pin C1)
32 Not connected
33 Not connected
34 Alarm supply (alarm siren)
35 Preparation for aggregates 2 (K-line for diagnosis)
36 CAN-bus A from ECU
37 CAN-bus B from ECU
38 Left front indicator
39 Right front indicator
40 Left front sidelight


Body Computer connector D

3 Instrument supply (+30)
4 Dipped beam switch on column
5 CAN-bus A to instrument panel
6 CAN-bus B to instrument panel
7 Indicator switch on column (left or right?)
8 Earth, passenger dashboard
9 Earth, passenger dashboard


Body Computer connector E

12 K-line for air bag control unit
20 Front fog lamps switch
22 Radio

Body Computer connector F

29 Hazard switch lamp
30 Indicator switch on column (left or right?)
31 Instrument supply (+15)
32 Heated rear window switch
33 Main beam switch on column
34 Hazard lamps switch
35 Rear fog lamp switch
36 Instrument supply (-)

NOTE: Pin numbering suggests D, E and F share a 36 way plug/socket


Body Computer connector Y (connects directly pin for pin to plug X on passenger fusebox)

1 Central locking supply
2 Top brake lamp signal (ponit between switch and lamp)
3 Reversing signal (point between switch and lamp)
4 Not connected
5 CAN-bus B to fusebox connectors E5 (radio) and D28
6 Heated rear window relay R11
7 CAN-bus A to fusebox connectors E17 (radio) and D10
8 Dipped headlamp relay R1
9 INT supply for body computer (ignition on, before F37)
10 Door locking motors
11 Door unlocking motors
12 Light system supply from ignition switch
13 INT supply for Instrument panel connector (ignition on after F37)
14 Sunroof, electric windows relay R13
15 Heater controls and cigar lighter illumination and number plate lamps
16 Not connected
17 Services / SMBT services supply
18 Body computer supply (immob., CAN-bus, sidelight, rear fog lamp)
19 Supply for indicators, hazards, instrument panel connector (via F53)
20 Central locking earth

red
 
At the risk of asking a very stupid question,

The black 40-pin connector, with the red bracket (the one one the left side in my left-hand drive punto), which one is that? A or C?

Thanks!
 
Hi ErikBooij,

Welcome to the forum. First of all, it is not a stupid question! Someone once said it is only stupid if you don't know and don't ask.

I'll assume that the Body Computer is the same on LHD and RHD cars.
From left to right, the sockets across the lower edge are A, B, C (with B being the vacant diagnostic OBD socket)

I don't have a picture for sockets D, E and F and as per my posting, I assume they are all combined. I expect this to be at the rear of the Body Computer but haven't probed round there (don't want to disturb Fiat wiring without good cause!)

Socket Y is vertical on the left side of the BC but you won't see this unless you removed the fuse panel (the corresponding plug X is on the back of the fuse panel).



red
 
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I'm so terribly sorry, I kinda forgot I asked here.

Thanks for your response, that's very helpful!

I'll come back when more questions arise. (y):D
 
this is very useful ..

i have an issue with my MK2b, i bought it with speedometer not working, i thought it might have been a sensor fault, however when i took it to a technician, i was surprised that the ABS were removed and i got those results:
1- U1601 - CAN line error
2-P0135 - Preheating resistance 1 above catal.
3- P0500 - Vehicle speed signal
4- P0115 - Water temperature sensor
5- U1601 - CAN network
6- U1602 - CAN line
there are 8 cables that are disconnected behind the BC and the technician didnt know what to do .
do you advise buying ABS control unit.. or there is a way to connect cables to make the speedometer works without connecting the ABS?
i appreciate your help
Stapy
 
Stapy,

Welcome to the forum. Not sure I can help much because I no longer own a Punto to play with but here goes....

As far as I know, speed sensing is derived from the ABS unit and sent to the body computer (Haynes call that the multi-timer) on Pin 7 of plug C. That fits with your speedometer not working while ABS ECU is absent. I wonder why the ABS ECU is not there? Just faulty so removed? Maybe you can get a second-hand one from as scrapyard? Before doing that, you might want to check that the wheel sensors are present. I don't think there's a way to make the speedometer work any other way. You say there are eight wires disconnected. Can you list the colours and I'll try to figure out what they are.

As for your diagnostic trouble codes: The ones referring to CAN line and CAN network could be loose/dirty connectors or one of the CAN controllers missing/damaged/incorrect type. Note that ABS is not on the CANBus, instead it is part of the K-line network.

The CANBus network is arranged in a star configuration from the body computer and connects to:
- Instrument Panel
- Engine ECU
- Electric steering
- Radio
- Diagnostic socket (EOBD)

"Preheating resistance 1 above catal" is saying that the resistance of the lambda sensor above the cat converter is giving incorrect resistance reading. Could be faulty sensor, loose/dirty connector or just a spurious error; might go away if reset.

"Water temperature sensor" should be obvious. Again faulty sensor or loose/dirty connector or spurious error; might go away if reset.

The "Vehicle speed sensor" is your missing ABS signals, so that isn't going to go away just yet!

PS. Saw your PM but thought best to elaborate here in case it benefits others.

red
 
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Hi the pin readout list for th bc unit you've provided is just what I'm looking for I've got a non abs mk2b 54 plate dynamic with flood damage to the bc unit manifesting with an intermittent speedo failure after between a 7to12 mile run, sometimes the steering warning light comes on as well,but after the car has cooled down faults disappear . I assume the mk 2 pin list will be different from the mk 2b pin list. Some of the pins on my control unit show signs of corrosion which is why I'm getting my speedo probs-could you tell me where to get a mk 2b list cheers
 
i thank you man for ur response
what about directly connect the pin 7 to pin 17 on connector C ? dont you think that the speedometer will work ?
 
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Cibo,

I don't know to what degree Mk2b wiring differs from Mk2. Most of my data relates to Mk2.

Speed sensing comes from ABS sensors (if you have ABS) otherwise it comes from a sensor in the gearbox. For non-ABS, Pin C17 on the BC is speedometer signal from the gearbox pulse generator, with Pin C 15 being the ground. Both wires go through an intermediate engine/front connector D04A.

As for a listing for Mk2b, most of my data for Mk2 came from a combination of the DTE manual and Haynes. I don't have any Mk2b data (other than looking in Haynes).

red.
 
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Stapy,


My advice? Don't short any pins - at best it won't do anything; at worst it will damage the BC. Pin C7 is expecting a signal from the ABS ECU. Pin C17 is expecting a signal from a gearbox pulse generator. However, the configuration in the Body Computer will determine which input is used to sense speed (i.e. C7 if ABS is configured as present, otherwise C17 will be used). If the vehicle should have ABS then it will need the ABS parts to get the speedo working.


red.
 
a few run out mk2b puntos have an extra wire from vss to underbonnet fusebox just to complicate maatters further,i wonder if this is to join up where abs to bsi would normally send its erronions:D
 
The stumbling block at that the body computer is a "black box" so we don't know what's going on inside there. I know it is initially configured with a list of peripherals that the car has (e.g. ABS) so that it knows what to expect on its inputs. If configured to have ABS, I doubt there's an easy DIY fix to circumvent this (though no doubt easy for a Fiat technician with the appropriate diagnostic hardware/software).

red.
 
The stumbling block at that the body computer is a "black box" so we don't know what's going on inside there. I know it is initially configured with a list of peripherals that the car has (e.g. ABS) so that it knows what to expect on its inputs. If configured to have ABS, I doubt there's an easy DIY fix to circumvent this (though no doubt easy for a Fiat technician with the appropriate diagnostic hardware/software).

red.

i think the bsi is indeed fitted to the appropiate model so non abs car cant be fitted with an abs bsi
have a look here if you fancy virginising bsi's but it wasnt cheap last time i enquired
http://www.nasratech.com/Fiat
 
Hi!

Anyone has a pinout for Mk2B? I need the functions for pins F14 and F18. These are connected to the Instrument Cluster's pin 6 and 7.
 
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