Cant connect to engine ECU

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My Name: nesc76

Member
Posts: 5
Joined: Fri Apr 21, 2017 1:32 pm
Model: C3 2002-2005, Original shape model
Year: 2004 (54)
Engine Size: 1.6 (16v)
Fuel Type: Petrol
Mileage: 130000
Trim Level: Exclusive
Gearbox: Manual 5 speed
DPF: No
LHD or RHD: LHD
Engine name: TU5 16-valve (110 PS)

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Hi,

I’ am trying to use Lexia to check some information about my Citroen C3 2004 1.6 16V, and I’am having a problem connecting to the ECU trough lexia or OBD. Lexia errors is that it cant connect to the ECU.

This is a different kind of C3, since it was converted to electric. At some point after the conversion we lost the hability to communicate witht the ECU. It was working fine, but after a long time in the shop with the battery disconnected it just stopped responding. Of course, we could have broken something else as well.

We checked all the power/earth connections to the ECU and they are ok. Also checked fuses and they seem alright. We asked for the local dealer to reprogram the ECU and they did it and said its ok, but it didnt work.

I dont have any of the wires from the harness connected at this point (other than earth and power). Not sure if some of those are mandatory.

The car itself works without the ECU, but I loose the hability to get information from it (RPM, speed and etc) that are usefull. The driving assistance is also not working and I bellieve its because it cant get access to the engine rpm information.

I attached a file with the output from Lexia.

Any tip/idea on were to look for the problem is higly appreciated.

Thanks in advance.
Attachments
ECU_Locked.jpg
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My Name: Arfur Dent

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Posts: 3340
Joined: Sat Jul 23, 2011 3:47 pm
Model: C3 2002-2005, Original shape model
Year: 2002 (52)
Engine Size: 1.4 (16v)
Fuel Type: Diesel
Mileage: 100000
Trim Level: Exclusive
Gearbox: Manual 5 speed
DPF: No
LHD or RHD: RHD (UK)
Engine name: DV4 16-valve diesel (90 PS)
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Hi nesc76

Did you attach the correct screen shot?

The one you have uploaded only show you are connected to the BSI and doesn't show any attempt to connect to the engine ECU.
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My Name: C3driver52

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Posts: 1868
Joined: Sat Apr 30, 2011 7:40 pm
Model: C3 2002-2005, Original shape model
Year: 2003 (03)
Engine Size: 1.4 i
Fuel Type: Petrol
Mileage: 79984
Trim Level: VTR+
Gearbox: Manual 5 speed
DPF: No
LHD or RHD: RHD (UK)
Engine name: TU3 (75 PS)
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nesc76 wrote:I dont have any of the wires from the harness connected at this point (other than earth and power). Not sure if some of those are mandatory.
I would imagine you would at least need the communication lines and the power supply wires to at least get the engine ECU to respond. If it didn't have communication lines, how could it communicate :?:
My Name: nesc76

Member
Posts: 5
Joined: Fri Apr 21, 2017 1:32 pm
Model: C3 2002-2005, Original shape model
Year: 2004 (54)
Engine Size: 1.6 (16v)
Fuel Type: Petrol
Mileage: 130000
Trim Level: Exclusive
Gearbox: Manual 5 speed
DPF: No
LHD or RHD: LHD
Engine name: TU5 16-valve (110 PS)

Post

Arfur Dent wrote:Hi nesc76

Did you attach the correct screen shot?

The one you have uploaded only show you are connected to the BSI and doesn't show any attempt to connect to the engine ECU.
Thanks very much for the help.

I tought that one could give more details. This is the one with the failed to connect.

Please let me know any screen that might be usefull. I have Lexia at hand, so I can check any info.
Attachments
IMG_1333.JPG
My Name: nesc76

Member
Posts: 5
Joined: Fri Apr 21, 2017 1:32 pm
Model: C3 2002-2005, Original shape model
Year: 2004 (54)
Engine Size: 1.6 (16v)
Fuel Type: Petrol
Mileage: 130000
Trim Level: Exclusive
Gearbox: Manual 5 speed
DPF: No
LHD or RHD: LHD
Engine name: TU5 16-valve (110 PS)

Post

C3driver52 wrote:
nesc76 wrote:I dont have any of the wires from the harness connected at this point (other than earth and power). Not sure if some of those are mandatory.
I would imagine you would at least need the communication lines and the power supply wires to at least get the engine ECU to respond. If it didn't have communication lines, how could it communicate :?:
Sorry, I did not express myself correctly. The full harness is connected to the ECU.

What is not connected are the wires that go to engine sensors and alternator. Basically those that would stay loose if you remove the engine.

I might have disconnected something that should stay connected for it to communicate, but I cant find out what. I cant pinpoint what changed between whent it was working and when it stopped.

Thanks for the help.
User avatar
My Name: C3driver52

Guru
Posts: 1868
Joined: Sat Apr 30, 2011 7:40 pm
Model: C3 2002-2005, Original shape model
Year: 2003 (03)
Engine Size: 1.4 i
Fuel Type: Petrol
Mileage: 79984
Trim Level: VTR+
Gearbox: Manual 5 speed
DPF: No
LHD or RHD: RHD (UK)
Engine name: TU3 (75 PS)
Has thanked: 89 times
Been thanked: 66 times

Post

nesc76 wrote:
C3driver52 wrote:
nesc76 wrote:I dont have any of the wires from the harness connected at this point (other than earth and power). Not sure if some of those are mandatory.
I would imagine you would at least need the communication lines and the power supply wires to at least get the engine ECU to respond. If it didn't have communication lines, how could it communicate :?:
Sorry, I did not express myself correctly. The full harness is connected to the ECU.

What is not connected are the wires that go to engine sensors and alternator. Basically those that would stay loose if you remove the engine.

I might have disconnected something that should stay connected for it to communicate, but I cant find out what. I cant pinpoint what changed between whent it was working and when it stopped.

Thanks for the help.
This is tricky. It would be worth tracing back your steps. Maybe try another engine ECU to see if that can can communicate. You won't have the engine starting problem with a replacement ecu because you don't have the engine.
You can pick up just the ECU for around £20, have a look here for an ECU.

Other than checking fuses and connections to the BSI and BSM, its would be very difficult to guess which bit you changed has caused the problem.
My Name: nesc76

Member
Posts: 5
Joined: Fri Apr 21, 2017 1:32 pm
Model: C3 2002-2005, Original shape model
Year: 2004 (54)
Engine Size: 1.6 (16v)
Fuel Type: Petrol
Mileage: 130000
Trim Level: Exclusive
Gearbox: Manual 5 speed
DPF: No
LHD or RHD: LHD
Engine name: TU5 16-valve (110 PS)

Post

C3driver52 wrote: This is tricky. It would be worth tracing back your steps. Maybe try another engine ECU to see if that can can communicate. You won't have the engine starting problem with a replacement ecu because you don't have the engine.
You can pick up just the ECU for around £20, have a look here for an ECU.

Other than checking fuses and connections to the BSI and BSM, its would be very difficult to guess which bit you changed has caused the problem.
Thanks C3driver52.

I did try a different ECU and had the same problem. I'am trying to find out which wires would be key for that communication to work. I tried following the wires but not sure I got the right ones. Is there any wiring diagram and/or location diagram for those wires between the BSI and the ECU?

I'am tripple check the fuses as well. I know someone else also checked the maxi fuses, will check the ones inside the car.
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