Can this fault (lack of information) decrease overall performance of engine since it will work without knowing that car is actually moving..?
What kind of amplitude this signal is and how did you guys solve this issue?
Thnx!
Laki
Motronic M1.7 fault code "1252"
In my Alfa 75 which is converted to 24 valve (Motronic M1.7) I'm getting the error code 1252. I know that the code describes vehicle speed sensor fault. It's there because it is not connected like it used to be in AR 164.
Can this fault (lack of information) decrease overall performance of engine since it will work without knowing that car is actually moving..?
What kind of amplitude this signal is and how did you guys solve this issue?
Thnx!
Laki
Can this fault (lack of information) decrease overall performance of engine since it will work without knowing that car is actually moving..?
What kind of amplitude this signal is and how did you guys solve this issue?
Thnx!
Laki
Re: Motronic M1.7 fault code "1252"
hi!
I've got the same problem running my TS with Motronic M1.7 when I use late ECUs which incorporated this function (155s post '94 have this feature, '92 155 ECU doesn't).
I'll go to the junkyard next week to remove a 155 dashboard: I'm going to study the ratio between impulses and meters/miles for the 155 speedometer and then connect the speedometer input signal of the Motronic 1.7 in parallel with the 75 dashboard speedometer (maybe with a frequency multiplier or divider, depending on the results of the analysis from 155 speedometer).
I'll keep you updated!
Sorry for my poor English,
Diego
I've got the same problem running my TS with Motronic M1.7 when I use late ECUs which incorporated this function (155s post '94 have this feature, '92 155 ECU doesn't).
I'll go to the junkyard next week to remove a 155 dashboard: I'm going to study the ratio between impulses and meters/miles for the 155 speedometer and then connect the speedometer input signal of the Motronic 1.7 in parallel with the 75 dashboard speedometer (maybe with a frequency multiplier or divider, depending on the results of the analysis from 155 speedometer).
I'll keep you updated!
Sorry for my poor English,
Diego
Re: Motronic M1.7 fault code "1252"
Hi,
I found a '92 2000TS8v cluster... If both (75/Milano and 155) speedometer sensors are reading speed of differential pinion, the speedometers should have different ratios between signal frequency and car speed. This because 75 TS has 10/41 diff. ratio and 155 2.08v (both run on 195/60VR14) has 17/57 or something similar.
But... Connecting both speedometer to a square wave generator shows that 75TS's shows a little more speed than 155 up to 100km/h.
I've connected motronic speedometer signal input pin to the yellow (signal IN) wire on the 75 cluster (I have 4 wires from the speedo connected on the rear of the cluster: black GND, red +12v, white +12v supply to pulse generator, yellow signal from pulse gen.): error 1252 and failure light are gone...
I found a '92 2000TS8v cluster... If both (75/Milano and 155) speedometer sensors are reading speed of differential pinion, the speedometers should have different ratios between signal frequency and car speed. This because 75 TS has 10/41 diff. ratio and 155 2.08v (both run on 195/60VR14) has 17/57 or something similar.
But... Connecting both speedometer to a square wave generator shows that 75TS's shows a little more speed than 155 up to 100km/h.
I've connected motronic speedometer signal input pin to the yellow (signal IN) wire on the 75 cluster (I have 4 wires from the speedo connected on the rear of the cluster: black GND, red +12v, white +12v supply to pulse generator, yellow signal from pulse gen.): error 1252 and failure light are gone...
Re: Motronic M1.7 fault code "1252"
Wow, really nice info!
What about performance of engine? Is it same or changed? Found another 164 24v in whole piece and I'm preparing to measure the wave.
What about performance of engine? Is it same or changed? Found another 164 24v in whole piece and I'm preparing to measure the wave.
Re: Motronic M1.7 fault code "1252"
Hi!
I've tried an ECU from a 164 (ecu 0261200659 eprom 1267357022) which previously annoyed me with 1252 error code... now the light stays off but ECU cuts power when I reach approx. 95kmh ... maybe speedometer pulse signal from 164 has different frequency/speed ratio compared to 75... (and to 155)
I'm gonna find a 164 ecu with 1267358531 chip...
ps: the same (cut power @ 95kmh) happens with a '92 155 ECU (from workshop manuals this ECU hasn't speed sensor checking feature)... but this is a mistery (maybe speed limiting was enabled with "default" settings since there was no speedometer input signal connected to the motronic)... and the cluster I've removed at the junkyard was from that '92 155
How are your measurements and experiments going?
TIA,
D.
I've tried an ECU from a 164 (ecu 0261200659 eprom 1267357022) which previously annoyed me with 1252 error code... now the light stays off but ECU cuts power when I reach approx. 95kmh ... maybe speedometer pulse signal from 164 has different frequency/speed ratio compared to 75... (and to 155)
I'm gonna find a 164 ecu with 1267358531 chip...
ps: the same (cut power @ 95kmh) happens with a '92 155 ECU (from workshop manuals this ECU hasn't speed sensor checking feature)... but this is a mistery (maybe speed limiting was enabled with "default" settings since there was no speedometer input signal connected to the motronic)... and the cluster I've removed at the junkyard was from that '92 155
How are your measurements and experiments going?
TIA,
D.
Re: Motronic M1.7 fault code "1252"
Couldn't measure it, since car changed owner (I was lazy)... 
I went to diagnostic center and spoke with one of experts which claims that VSS doesn't influence on performance of car. It is related to trip computer and/or if your car is equipped with automatic transmission.
Why are you looking for this 1267358531 chip?
I went to diagnostic center and spoke with one of experts which claims that VSS doesn't influence on performance of car. It is related to trip computer and/or if your car is equipped with automatic transmission.
Why are you looking for this 1267358531 chip?
Re: Motronic M1.7 fault code "1252"
Possibly cruise control is affected as well I guess?
Mats Strandberg
-Scuderia Rosso- Now burned to the ground...
-onemanracing.com-
-Strandberg.photography-
GTV 2000 -77 - Died in the fire.
155 V6 Sport -96 - Sold!
-Scuderia Rosso- Now burned to the ground...
-onemanracing.com-
-Strandberg.photography-
GTV 2000 -77 - Died in the fire.
155 V6 Sport -96 - Sold!
Re: Motronic M1.7 fault code "1252"
I'm looking for that chip to find out if there are differences between that and 022 I already own.. maybe nothin' related to speed control...
signal is a square wave on 75 (0-12v), I created a frequency divider (with a 4013 d type flipflop): now 164 ecu cuts power @ 190kmh...
but I'm still looking for a "running" 164 to measure freq (and calculate freq/speed ratio, at least for the 2.0TS version.)... hmm I think that I'll take a 164 cluster and try with a function generator
ps: I don't own an oscilloscope (university labs help here ) but I own a frequency meter...
signal is a square wave on 75 (0-12v), I created a frequency divider (with a 4013 d type flipflop): now 164 ecu cuts power @ 190kmh...
but I'm still looking for a "running" 164 to measure freq (and calculate freq/speed ratio, at least for the 2.0TS version.)... hmm I think that I'll take a 164 cluster and try with a function generator
ps: I don't own an oscilloscope (university labs help here
) but I own a frequency meter...Re: Motronic M1.7 fault code "1252"
and I don't see any performance difference at normal/low speed driving (under 120 kmh)... maybe it's my imagination but I noticed a different behaviour at low rpms with lower gears [rpm fall slower under 1800 rpm with speedo signal supplied to ecu]
Re: Motronic M1.7 fault code "1252"
Good note, keep up the good work!