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Discussion Starter #1
Noob question here, but does the S3 and earlier have a diagnostic port? Seems like the ECU does not have this. I ask because I am into electronics and curious if anyone has ever made a device to read all sensors and such.
 

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But Mad North-Northwest
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No, the S3 L-Jetronic is all analog electronics and lacks diagnostics. S4 got OBD1 in 1991, but even then there wasn't a diagnostic port, it flashed codes via the check engine light.

Bosch did make an L-Jetronic tester for shops, IIRC, but they were not common.
 

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Discussion Starter #3
Perhaps I can stake a stab at something. Long term Covid project, it would be fun.
 

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Administrator
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The Bosch tester plugged in between the car's wire harness & the ECUs (computers). One then turned a rotary switch to run though testing the various inputs (from the sensors). As far as I know, it did not test the ECU itself. If all the inputs checked out OK the nest step was 'replace ECU'. Its main advantage was that one could fairly quickly test all the components and it also tested that the inputs were getting to the ECU - if a component failed you were advised to check at the sensor to rule out a fault in the wiring from the sensor to the wire harness plug.

1669471
 

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Premium Member
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Discussion Starter #5
The Bosch tester plugged in between the car's wire harness & the ECUs (computers). One then turned a rotary switch to run though testing the various inputs (from the sensors). As far as I know, it did not test the ECU itself. If all the inputs checked out OK the nest step was 'replace ECU'. Its main advantage was that one could fairly quickly test all the components and it also tested that the inputs were getting to the ECU - if a component failed you were advised to check at the sensor to rule out a fault in the wiring from the sensor to the wire harness plug.
Pretty old school :). I am thinking a device to capture the info and bluetooth it to an app on your phone. This way you can monitor engine components while you are driving. I think my main challenge will be geting in between the connector and the ECU. Did a quick search and nothing exists that can get in between. Will take some creativity.
 

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Noob question here, but does the S3 and earlier have a diagnostic port? Seems like the ECU does not have this. I ask because I am into electronics and curious if anyone has ever made a device to read all sensors and such.
It wasn't unti lthe 1990 model with Motronic injection that you had any diagnostics. With Motronic, you had a single ECU and a check engine light that would flash a code if you hit the button behind the seat by the ECU.
Still rather primitive.
 
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