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Discussion Starter #1
Hi there,

I've got an Alfa Romeo 33 1.7 1994, which has the Bosch Motronic MP3.1 injection/ignition system.
I'm looking for info about reading the fault codes from this ECU.
As I understand, it should be possible to connect a switch and read the codes from either, one of the dashboard lights, or a light/LED I connect myself.

I have been looking for a 4-pin T2 'flashing code diagnosis connector', without success.
I think I did find the 2-pin S49 'MP31 controle unit switching connector', Although this connector is also hanging of the ECU, I'm not 100% sure it is the S49.(1st image)
And I found the 3-pin T1 'connector for alfa tester' which is basically just hanging of the ECU.(2nd image)

Are any of these the connectors I need to use, and to which pins will I wire the switch and/or LED?

I believe I have to turn the ignition to on but keep the engine off and then short the switch for 5 seconds?
Any other/additional info about how to operate the diagnosis is also welcome.

Thanx in advance
 

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Hi,

The red connector on the picture is the 1.5 - 1.7 injection&ignition map selector. Normally the
terminals of this connector should be shorted when 1.7 engine is installed.

The flashing code pin of the Motronic MP3.1 ECU is not connected to the wiring harness. Once
i have removed the top cover of the Motronic unit and checked the flashing pin from inside of
the unit, but no matter what have I done with the externally connected switch, the flashing code pin
was remained in "steady high" state.

Theoretically the self diagnosis and the actuator tests (fuel vapour solenoid, idle actuator, injector valves)
can be initiated from the T1 connector with a switch. I have tried the actuator tests, but no success either.
I think i still have my notes, if you're intrested i can dig them up for you this weekend.
 

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Discussion Starter #3
Thanx for the info

The red connector on the picture is the 1.5 - 1.7 injection&ignition map selector. Normally the
terminals of this connector should be shorted when 1.7 engine is installed.
Do you mean the two pins should somehow be attached together ?

I think i still have my notes, if you're intrested i can dig them up for you this weekend.
I'm very interested in any info about this, but I probably try to get additional info elsewhere as-well.
I'm a bit worried about shorting the wrong wires !

The flashing code pin of the Motronic MP3.1 ECU is not connected to the wiring harness.
A bit odd, isn't it ?
I have to say, in this case it's probably not a bad idea to connect LED and the switch directly to the ECU.
I included an image of the pin-layout of the MP3.1, if you could tell me what you think is the flashing code pin and if you know the pin for the switch.

Ps.: I expected this would be the easy way to read the fault-codes, but maybe it is easier to connect the T1 straight to my serial connector on my pc (down-side is that I have to take my PC into the freezing garden).

Regards, and thanx again
 

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Do you mean the two pins should somehow be attached together ?
Yes, on the 1.7 models there's a plug inserted into this connector,
which shorts these terminals. As far as i know the ECU must be
"rebooted" by interrupting it's power supply in order to check the
presence of this short circuit and use the injection&ignition map
accordingly.

If this short circuit is missing, the 1.7 engine will run lean
(mainly at low ambient temperatures, resulting poor throttle response)
until the closed loop mixture control is enabled.

I'm very interested in any info about this, but I probably try to get additional info elsewhere as-well.
I'm a bit worried about shorting the wrong wires !
OK, no problem.

A bit odd, isn't it ?
I have to say, in this case it's probably not a bad idea to connect LED and the switch directly to the ECU.
I included an image of the pin-layout of the MP3.1, if you could tell me what you think is the flashing code pin and if you know the pin for the switch.
Yes, maybe the flashing function is not implemented in this type of ECU,
that would explain why pin#17 (the flashing code pin) is marked as N.C.

Ps.: I expected this would be the easy way to read the fault-codes, but maybe it is easier to connect the T1 straight to my serial connector on my pc (down-side is that I have to take my PC into the freezing garden).
On the 16V models much easier to perform this, because besides the "Alfa tester"
diagnostic connetor (T1) there's a dedicated connector for flashing code reading (T2).
This T2 connector is completely omitted from the 33 models with Motronic MP3.1

About the serial connection with PC: be careful, because RS-232 of the modern PC's
are often working with 5V TTL line voltage (but 3,3V versions also exists) and may not
tolerate the 12V car line voltage on the Rx pin. At the other hand the Tx pin voltage may
not enough to drive the ECU's Rx line.
 

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Discussion Starter #5
Have been really busy these days, so didn't find the time to reply sooner.

Anyway... thanx for all the info/help :)

If this short circuit is missing, the 1.7 engine will run lean
Strangely enough, my engine seems to use a lot of fuel :?
I shorted the connection and disconnected the battery for 5 minutes.
Although resetting the ecu always seems to help my car running better, I am unsure if shorting this plug helped anything. I have to take the car for a longer drive another day.
For the problems of my engine I will probably start another thread one day (soon).

... maybe the flashing function is not implemented in this type of ECU,
that would explain why pin#17 (the flashing code pin) is marked as N.C.
I did connect pin#17 to a cable and tried to connected according the info I have, but did not get very far. I'm afraid that you may be right, maybe it's not implemented :(.
According to some info on the web somewhere, I found that somehow they've produced MP3.1's with and without this feature.
But I do not give up this easy...

I found 'two' ways it could be connected, see the pictures below.
I'm hoping you (or anybody from this forum) have got some more or better info about the flash feature...?
 

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For me high fuel consumption was caused by dead oxygen sensor. After the sensor
replacement the fuel consumption was dropped significantly.

As far as i know the flashing code reading works the same manner on Motronic MP3.1
and Motronic ML4.1 ECUs. The LED (and resistance) or light bulb (12V 1.2W max) should
be connected between +12V and pin#17 (diagnostic pin) like on the 1st schematics.
But the other hand, grounding the diagnostic pin is not seems a good idea for me (2nd schematics).
 

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The switch should be connected between light blue wire terminal (pin "A")
and the black wire terminal (pin "B" - middle pin) of the T1 connector.
 

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Discussion Starter #8
It done the trick :)

Thanx a lot LoneWolf33, I did get some codes out of it.

Shorting the light blue and the black wire of the T1 connector for about 3 seconds done the trick.
Next time I'll make a small box with the light and an actual switch and see if I can analyze the codes. And probably have to start a new topic about the engine issues I'm experiencing :)

Hopefully this topic can be handy for others as-well.

Thanx again
 

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Discussion Starter #9
Fault code chart

I'm looking for the exact fault code chart.
In my search on the web I came across two totally different versions, so I'm wondering which one is the right one ?

Any idea ?

regards
 

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Hi,

The 2nd one seems to suit to Opel Vectra A / Calibra models
which were fitted with Motronic 2.5 or Motronic 2.8 ECUs.
There could be big differences in the fault codes between the different
Motronic ECU models. For example many fault codes in Motronic 2.5
simply not exists in Motronic MP3.1 and the fault codes for the
same fault symptoms are different as well.

The fault codes and the flash codes are not the same, there's a
cross reference between them, e.g.: the flash codes of the MP3.1 unit
are arranged in four digit groups (as far as I know), while the fault codes are
three digit numbers.
 

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Discussion Starter #11
second

yes, I'm guessing it's the second one as-well, looking at the codes I was getting.

Thanx, again

Ps.: For anybody interested, here is a reasonable link for info about the codes.
 

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Guessing is wrong :(

This is getting real funny, I'm getting codes but do not know what they are standing for.
I pulled out some cables to invoke an error, but it didn't seem to coexist with the charts from above.
Then I came across some other chart which uses the 4 digits (12xx), but its telling me I have an error from a knock sensor.

Question:
Does the Alfa Romeo 33 1.7 ie actually have a knock sensor (can't find anything in the manual about it).

Ps.: There is another (again, totally different :confused:) chart I found in the Haynes-Techbook what otherwise could be promising and even did send Bosch an email (not much chance, but who knows).

Still wonder why you never got any flash-codes read from your ECU?
Is it also the Motronic 0 261 200 658 ?
There seem to be other MP3.1's with different reference numbers.

regards
 

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Hi,

There's no knock sensor on AR33s.

Yes, the ECUs with Bosch number 0 261 200 658 were used in the
late 1.5 and 1.7 IE models (in mine also). There were minor updates on the ECU
during the production, but the number remained the same.

Actually my ECU wasn't intact, it was already opened by someone before.
There were suspicious marks on the ECU's housing and on the casing
of the MAP sensor inside as well. I've found the MAP sensor was opened
up by someone (this is a non serviceable part, therefore no reason to open up the sensor...)
So i guess the person who made this butcher work might damaged the flash code circuitry also.

Since then i've replaced the ECU with an intact one, but haven't tried to get flash codes
from the "new" unit. Maybe i'll give it a shot again when the weather gets warmer...

Besides Alfa33, MP3.1 ECUs were used in Peugeots and Citroens as well.
Some other Motronic MP3.1 Bosch numbers:
0261200200, 0261200212, 0261200213, 0261200214, 0261200217

0261200695 - this one was used in the early 145/146 1.6 Boxer models.
As far as i know the 0261200658 is the only MP3.1 ECU with dual ignition/injection map.

I still think error codes of other Motronic units (fault or flash) doesn't apply to MP3.1
and vice versa.

If you get anwser from Bosch, don't hesitate to share with us.
 

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Reply from Bosch...

The reply from Bosch was basically useless.
They send me some info in German, but the chart (all I was asking for) they did not find.
I'm still in the process of translating it. But I'm not even sure the info is for the MP3.1

While translating from German, I got the brilliant idea to Google with some German key words and found some interesting forum topic(English translation) of some guy who had done the flashing-code diagnosis on an Alfa Romeo 33 1.7 ie with motronic MP3.1.
Do not be fooled by Google translating "MP 3.1" into "MP 1.3"
This chart is in line with the the charts I found for the ML4.1 in the Haynes-Techbook and on http://www.troublecodes.net/(click "Disclaimer page" and "Trouble codes" -> "Alfa Romeo")
And the chart corresponds with the errors I purposely invoked by disconnecting some cables.

On my car I was reading error code 1223, 1225 & 1224 (in that order).
So according to this information I do have a faulty Lambda :cry: and air temperature sensor.
Today I've been testing all the wiring and measured the resistance in the air temperature sensor. And all was fine :confused:

Questions:
1. Is there any chance that the faulty Lambda invokes an "air temperature sensor" error ?
2. How is your German ? :p
 

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Questions:
1. Is there any chance that the faulty Lambda invokes an "air temperature sensor" error ?
2. How is your German ? :p
1. IMHO no. But the lambda correction control and lambda sensor faults are often
coming up together.

2. Ich verstehe etwas Deutsch

The explanation of error codes 1212, 1213, 1215 and 1221 are
seem to be Motronic ML4.1 related.
 

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ECU scantool

The weather is warm enough to play around with the Alfa Examiner scantool,
which I got for repair (burnt SMD parts inside and a damaged connector).

The result can be watched on the following link:
Alfa Examiner on Alfa33 1.5IE (1994) - YouTube

Because I think connecting a 33 to a scantool is not happens quite often,
for a moment I had a strange/surreal feeling as I saw as the operating parameters
are appearing on the screen. Besides the flash code this car is capable
to online diagnosis.... a few years back the 33 models have only carbs and points
in the ignition...
 

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Hello,
It doesn't get clear to me wich one of the schematics is suitable for flash code. I have an alfa 146 1.7 16v and the error light is on about one week.
Thanks a lot
 

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Hi,

The flash code diagnostics doesn't apply to 146 1.7 16V. It has a different ECU, which has only serial
diagnostics capability (requires a tester to read out the stored faults).
 
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