Citroen BX TZi ECU diagnostic codes

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barryg

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I'm having the 'engine autodiagnostic lamp' coming on for up to 10 minutes at a time. Car still runs fine, but I know it is trying to tell me something.

It's got a Motronic ECU, does anyone know how to get the diagnostic codes out of it? Does it need a special reader, or is there a simple bridge these connectors and count the flashing on the light?

Thanks,

Barry.
 
barryg said:
I'm having the 'engine autodiagnostic lamp' coming on for up to 10 minutes at a time. Car still runs fine, but I know it is trying to tell me something.

It's got a Motronic ECU, does anyone know how to get the diagnostic codes out of it? Does it need a special reader, or is there a simple bridge these connectors and count the flashing on the light?

Thanks,

Barry.
Click to expand...

Barry,

Mike Tippett from Vancouver, a Pug owner posted a while back that there was a simple way of doing this but from memory he didn't get all that friendly a reception off a couple here so didn't elaborate.
I'd suggest that you do a search on all of his postings using the search facility & look it up.
I have the necessary codes here on a CD but somehow I can't get them to spit out.

Alan S
 
I think my dad has been looking into this, and is actually making (slowly) some software to plug a laptop into the ecu and read the codes. PM Ken W and ask, i'm not sure how the project is going.

Dave
 
I think that Bruce Elsegood (Father Goose) in Sydney, has one of the machines to read the codes - bought at the disposal sale of the failed North Shore dealership?

Paul
 
Thanks everyone for the suggestions.

Alan S said:
Barry,

Mike Tippett from Vancouver, a Pug owner posted a while back that there was a simple way of doing this but from memory he didn't get all that friendly a reception off a couple here so didn't elaborate.
Click to expand...

Found that thread, and you're correct the reception wasn't good. Must say I don't understand the flak. What's wrong with trying to diagnose problems yourself, esp. when the ECU can give you very strong hints? Vested interests perhaps?

Ok, for the record here's how to pull the codes. This should work for Peugeot 405s & BX16v/mi16s as well.

Locate the 2 pin diagnostic connector. On the BX TZi it's on the driver's side near the sphere. Stick a wire into pin 1. Pin 1 is as shown below:

__ __
| x x | Looking at the pins, keep notch to the top, pin 1 is left hand pin.
------
^ pin 1

Here's the recipe to pull the codes:

http://www.vectorbd.com/peugeot/files/405ecu.pdf

Basic thing is, with the ignition on, ground pin 1 for 3 seconds, then get the code from the check engine light flashing. It gives you one code per 3 second grounding, first code is 12, last is 11. Wait for check engine light to come on continuously before each 3 second grounding. Once the code 11 is reached, the ECU can be reset of all stored fault codes by a 10 second+ grounding.

The BX is giving mostly code 34s, canister purge electro valve. Apparently this just floats inline on hoses somewhere around the plenum chamber. All the hoses around here are pretty sus, esp the oil filler ones. I'm going to replace them all next weekend. I'm also getting code 31, air leak at intake. My guess is that the hoses are causing this as well.

Barry.
 
barryg said:
Thanks everyone for the suggestions.

Basic thing is, with the ignition on, ground pin 1 for 3 seconds, then get the code from the check engine light flashing. It gives you one code per 3 second grounding, first code is 12, last is 11. Wait for check engine light to come on continuously before each 3 second grounding. Once the code 11 is reached, the ECU can be reset of all stored fault codes by a 10 second+ grounding.

Barry.
Click to expand...

Barry,

Thanks for the recipe. I don't quite understand your second to last paragraph (above), however, and would appreciate a few more words if you don't mind.

1. When you say "ground pin for 1-3 seconds", does that mean then disconnect immediately to start counting the number of flashes of the check engine light, or do you mean something else?

2. Do you then reground it for another 3 seconds for the next set of numbers beginning with 2?

3. How do you know you have reached code 11 and that you can then purge the stored fault memory by grounding for 10 seconds?

These may seem naiive questions, but it isn't quite clear to me. As I'm currently buying a BX, I have some interest......

Thanks

JohnW
 
John,

Sorry for the confusion, let's see if I can clear it up a bit.

JohnW said:
Barry,

Thanks for the recipe. I don't quite understand your second to last paragraph (above), however, and would appreciate a few more words if you don't mind.

1. When you say "ground pin for 1-3 seconds", does that mean then disconnect immediately to start counting the number of flashes of the check engine light, or do you mean something else?
Click to expand...
I mean take the wire attached to pin 1 on the diagnostic connector, and touch chassis ground for three seconds, then disconnect. The code should start being flashed out about 2 seconds later.
JohnW said:
2. Do you then reground it for another 3 seconds for the next set of numbers beginning with 2?
Click to expand...
Yes, once a code has been flashed & the check engine light is lit continuously one should ground for 3 seconds again to get the next stored code to be flashed out. There is no real order that the codes come out (possibly they are stored chronologically), except code 12 is the very first code, and code 11 is the very last code.
JohnW said:
3. How do you know you have reached code 11 and that you can then purge the stored fault memory by grounding for 10 seconds?
Click to expand...
Code 11 is reached when the error code flashed is 11.
JohnW said:
These may seem naiive questions, but it isn't quite clear to me. As I'm currently buying a BX, I have some interest......

Thanks

JohnW
Click to expand...

OK, here's a revised recipe. It's pretty easy to do once you get the gist of what needs to be done.

Locate the 2 pin diagnostic connector. On the BX TZi it's on the driver's side near the sphere. Stick a wire into pin 1. Pin 1 is as shown below:

__--__
| x x | Looking at the pins, keep notch to the top, pin 1 is left hand pin.
-------
^ pin 1

Using the wire attached to pin 1 as shown above, do the following:

1/ Turn ignition on (but don't start the engine)

2/ Ground pin 1 using the attached wire for 3 seconds. This means touch the wire from pin 1 to some convenient chassis ground point for three seconds, then disconnect from ground. One could connect a switch (one side pin 1, other side chassis ground) for this purpose, but I found just touching the wire on something chassis ground worked fine.

3/ You should see the code 12 flashed on the check engine light

4/ wait until the check engine light is lit continuously. This is about 3 seconds after the code has flashed.

5/ ground the wire from pin 1 again for 3 seconds.

6/ The next stored code will be flashed, or the code 11 is flashed indicating end of stored codes.

7/ if not code 11 repeat steps 4-6.

8/ Once code 11 has been flashed the ECU can be cleared of stored codes by grounding the wire from pin 1 for 10+ seconds when the check engine light is lit continuously.

9/ For an ECU with no stored codes this process will yield code 12 followed by code 11.

10/ Not all error conditions will result in the check engine light coming on whilst driving, but the codes will be stored. Thus, this may be a worthwhile thing to do every so often just to make sure all is well.

Barry.
 
barryg said:
John,

Sorry for the confusion, let's see if I can clear it up a bit.


I mean take the wire attached to pin 1 on the diagnostic connector, and touch chassis ground for three seconds, then disconnect. The code should start being flashed out about 2 seconds later.

Yes, once a code has been flashed & the check engine light is lit continuously one should ground for 3 seconds again to get the next stored code to be flashed out. There is no real order that the codes come out (possibly they are stored chronologically), except code 12 is the very first code, and code 11 is the very last code.

Code 11 is reached when the error code flashed is 11.


OK, here's a revised recipe. It's pretty easy to do once you get the gist of what needs to be done.

Locate the 2 pin diagnostic connector. On the BX TZi it's on the driver's side near the sphere. Stick a wire into pin 1. Pin 1 is as shown below:

__--__
| x x | Looking at the pins, keep notch to the top, pin 1 is left hand pin.
-------
^ pin 1

Using the wire attached to pin 1 as shown above, do the following:

1/ Turn ignition on (but don't start the engine)

2/ Ground pin 1 using the attached wire for 3 seconds. This means touch the wire from pin 1 to some convenient chassis ground point for three seconds, then disconnect from ground. One could connect a switch (one side pin 1, other side chassis ground) for this purpose, but I found just touching the wire on something chassis ground worked fine.

3/ You should see the code 12 flashed on the check engine light

4/ wait until the check engine light is lit continuously. This is about 3 seconds after the code has flashed.

5/ ground the wire from pin 1 again for 3 seconds.

6/ The next stored code will be flashed, or the code 11 is flashed indicating end of stored codes.

7/ if not code 11 repeat steps 4-6.

8/ Once code 11 has been flashed the ECU can be cleared of stored codes by grounding the wire from pin 1 for 10+ seconds when the check engine light is lit continuously.

9/ For an ECU with no stored codes this process will yield code 12 followed by code 11.

10/ Not all error conditions will result in the check engine light coming on whilst driving, but the codes will be stored. Thus, this may be a worthwhile thing to do every so often just to make sure all is well.

Barry.
Click to expand...

Thanks for putting that down, Barry.

So after a 3 second grounding if, for example the code were 34, I'd get 3 flashes, a pause, then 4 flashes of the dashboard light, then I'd need to ground it for 3 seconds again to get the next one? At the end I get a single flash, a pause, then a single flash, i.e. 11?

Thanks for that.

JohnW
 
JohnW said:
Thanks for putting that down, Barry.

So after a 3 second grounding if, for example the code were 34, I'd get 3 flashes, a pause, then 4 flashes of the dashboard light, then I'd need to ground it for 3 seconds again to get the next one? At the end I get a single flash, a pause, then a single flash, i.e. 11?

Thanks for that.

JohnW
Click to expand...

Almost there. I'll quote your statement & fix it:

So after a 3 second grounding if, for example the code were 34, I'd get 3 flashes, a pause, then 4 flashes of the dashboard light, then I'd need to ground it for 3 seconds again when the dashboard light is lit continously, about 2 secnds after the last flash to get the next one? At the end I get a single flash, a pause, then a single flash, i.e. 11?

Barry.
 
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