Clear SRS errors without MUT

[ano1]

PIN 7 oder PIN 12 on OBD2. Early models of Galant EA have PIN12 on OBD2 for SRS-ECU, later models have PIN 7 on OBD2 for SRS-ECU.
Checking in the meantime with my Mitsu Dealer, when changes were made....

I believe when on PIN 7 other codes on OBD2 for accessing SRS are additionally needed.

If this information is well known, please ignore it.

Attached schematics.
regards
ano1
Late EA models:

Early models:

 

[BCX]

Finally got around to check my vr4, it matches wiring diagram for 2000 onwards.

My 1998 wiring diagrams show pin 12.

1999 supplement diagrams dont have srs diagrams

So the change was between 1998 and 2000, presumably june 2000 onwards.

So I think we got to the bottom of the confusion then.

Might have to get a hold of an older SRS module and sniff out pin 12 with the MUT.

 

[kc427]

I understand a little bit more after checking other manuals I have in my computer, and summarize as the following table:

Workshop manual	Trim	SRS Connector-pin	OBD2 pin
Japanese Galant EA/EC	Without side air bag	C53-11	12
	With side air bag	C52-16	12
English UK 97 Galant	L.H. with side air bag	C43-16	12
	L.H. without side air bag	C44-11	12
	R.H. with side air bag	C43-16	12
	R.H. without side air bag	C44-11	12
English unknow year	Without side air bag	C44-16	7
	With side air bag	C44-16	7

Now, we can see that some version use OBD pin7, and some use pin12. Also, the SRS connectors between "with side air bag" and "without side air bag", ie, the Cxx connectors are different, and therefore, the SRS module units are different. I guess it is due to some VR4 has leather seats which have side air bag, and cloth seats without side air bag.

Also, I did a test in my friend's garage using Launch X431, and can read the SRS code, but cannot erase. I will post more details tomorrow, as I am very sleepy now.

 

[kc427]

Finally got around to check my vr4, it matches wiring diagram for 2000 onwards.

My 1998 wiring diagrams show pin 12.

1999 supplement diagrams dont have srs diagrams

So the change was between 1998 and 2000, presumably june 2000 onwards.

So I think we got to the bottom of the confusion then.

Might have to get a hold of an older SRS module and sniff out pin 12 with the MUT.

View attachment 64639

Just a note, the Japanese wording there saying "with side air bag"

 

[BCX]

Just a note, the Japanese wording there saying "with side air bag"

Was on my phone sitting in the vr4 when looking. Just checked, with side airbags and without use pin 7 on the diagrams I have (Jun 2000 onwards) but pin 12 on 1998 diagrams.

1999 supplement doesn't show SRS, so assume need to refer to 1998 diagrams.

 

[kc427]

Was on my phone sitting in the vr4 when looking. Just checked, with side airbags and without use pin 7 on the diagrams I have (Jun 2000 onwards) but pin 12 on 1998 diagrams.

1999 supplement doesn't show SRS, so assume need to refer to 1998 diagrams.

Yes, I also has the Japanese 1999 supplement manaul, and only saying the ASC/AYC/ABS/TCL, doesn't mention anything about SRS, so also agree that assume SRS is the same as 1998. So in that case, assuming that all the JDM Galant using OBD pin 12 for the SRS. However, some version of the Galant from the rest of the world, may use the OBD pin 7.

 

[BCX]

My Galant is JDM as I imported it to AU (built october 2000) and the wiring diagrams I've got are for JDM Galant/Legnum.

So at some point it changed.

JDM wiring diagrams for June 2000 onwards is the first I've seen where pin 7 is referenced (screenshot I posted previously), and my Galant matches these diagrams.

If you could try and see if Launch can communicate on pin 12 with your bench setup, and see if you can sniff the traffic, that would be interesting.

Looking at Magna, they use pin12, so will grab one from wrecker and try with the MUT.

 

[kc427]

My Galant is JDM as I imported it to AU (built october 2000) and the wiring diagrams I've got are for JDM Galant/Legnum.

So at some point it changed.

JDM wiring diagrams for June 2000 onwards is the first I've seen where pin 7 is referenced (screenshot I posted previously), and my Galant matches these diagrams.

If you could try and see if Launch can communicate on pin 12 with your bench setup, and see if you can sniff the traffic, that would be interesting.

Looking at Magna, they use pin12, so will grab one from wrecker and try with the MUT.

You are right. I just checked with ASA part number, and found that upto 1999, there are 2 types of SRS unit, MR213293(no side). MR309232(side). From 2000, the SRS are MR522968(no side) and MR522969(side). From this information, it can explain why your year 2000 using OBD pin7, and my year 1998 using OBD pin12 for the SRS communication.

About using the Launch with my bench setup, that's I am going to share my findings next. Let me gather all information and reply in the next post.

 

[kc427]

OK, let me share what I found by using the Launch X431 with my bench setup, by using MR213293 with OBD pin 12 only(no pin 7). Since I am from Hong Kong, so I hope you understand what I mean with my poor English, and all the X431 is in Chinese wordings. In short, the communication is successful.

I went to my friend's friend's garage to use that Launch X431, and then connect my bench setup SRS. You see the version number below photo:

After I started to connect, and then after a little bit longer time, maybe 2 minutes later, I could see the X431, and the system info was 702B:

Good. Then after that, I tried to read the fault code, and found 22 and 25, which is driver's side air bag, and passenger's side air bag problem. I knew I used a 1W 3.9ohm resistors on the harness to fool the SRS, so, I didn't understand why still has these 2 code:

Then I thought it might be the code stored before because this SRS is 2nd hand from ebay. So I selected the erase on the X431, and trying to erase the code. After pressing the erase code on X431, it said it's success, and so I read the code again to confirm that, but unfortunately, code 22 and 25 were still there, it's not erased! I repeated this erase 3 times, and still got the code. So I don't understand why, but I just guess, it maybe some other problem that couldn't erase the SRS code, or maybe this 2nd hand SRS deployed the air bag before when it was using, so once deployed, cannot be erased:

After I back home and check again code 22 and 25 from the manual, and find that it says something like open circuit of the airbag or connection contacts. Then I check the resistors I used again, and surprisingly, no measurement on the resistors! I don't know why the resistors are broken, and thinking, no wonder after erase by X431, code 22 and 25 are still there, because the resistors are broken.

So, next step, maybe I cannot use 1W carbon film 3.9 ohm resistors, because it maybe broken during my soldering, and simple just use normal 1/4w metal film resistors. After changing the resistors, need to find a chance to access the X431 again and see everything is fine or not.

In summary, using X431 on MR213293 with OBD pin 12, communication is OK, SRS code can be read successfully. Erase needs to be confirmed.

 

[BCX]

Nice!

702b looks like the SCC (yet to work out what that SCC stands for, but seems to be an cal id or similar)

Three values you can log look the same as the MUT

Fault time period 1
Fault time period 2
Number of erases

So seems functionality between the two srs computer types (old and new) is the same, just the comms is different.

Keen to see what you can sniff out.

I've got a lot of hand written notes so will document what I've found with the later srs computer in terms of requests, etc.

 

[kc427]

Interesting findings. I removed the SRS connector harness and measured the 2 resistors for driver side and passenger side airbag pins, both were about 0.3-0.5 ohm, that's why I thought there is a short on the resistors. After I de-soldered and measured the resistors again, they were all good. After removed the resistors, I measured the connectivity of the pins for the driver side air bag and passenger side air bag, they both were connected/shorted. I am surprised about that. After checking carefully, I found that there is a metal contacts which connects the pins together if the connector is removed/free. I inserted something to block the metal contacts, and measured the pins again, and there was no more connectivity.

That dark grey metal contacts, will short the pins together if the plug is out:

Tried to insert something to block the connections, and the pins are then no connectivity. The SRS unit itself has already have something to block the connection, therefore after plug in the connection, the pins no connectivity:

So, the resistors are good, and seems alright, however, I still got code 22 and 25. I am thinking, is resistor 3.9 ohm to high for the SRS?

 

[kc427]

Nice!

702b looks like the SCC (yet to work out what that SCC stands for, but seems to be an cal id or similar)

Three values you can log look the same as the MUT

Fault time period 1
Fault time period 2
Number of erases

So seems functionality between the two srs computer types (old and new) is the same, just the comms is different.

Keen to see what you can sniff out.

I've got a lot of hand written notes so will document what I've found with the later srs computer in terms of requests, etc.

How to sniff out the data? I don't have logic analyzer to trace the data. Or, I can use a USB-TTL and tap the OBD pin 12(old SRS) and capture the serial data?

 

[BCX]

Usually use oscilloscope to check voltage levels (with serial decoding) but eventually move to logic analyser.

My logic analyser is 5v input, so usually have to make a resistor divider to bring voltage down.

You might be able to do it with usb-ttl and voltage divider.

If its anything like kline comms... Usually MUT sends a byte, and then recieve a byte 10-15milliseconds later.

 

[kc427]

Usually use oscilloscope to check voltage levels (with serial decoding) but eventually move to logic analyser.

My logic analyser is 5v input, so usually have to make a resistor divider to bring voltage down.

You might be able to do it with usb-ttl and voltage divider.

If its anything like kline comms... Usually MUT sends a byte, and then recieve a byte 10-15milliseconds later.

So, it's kind of 12v TTL signal?

 

[BCX]

Yep, 0-12v (closer to battery voltage)

 

[kc427]

Thinking about an alternative solution. Opened up the metal case, and found that the CPU is MH3292F16, and using 93C56 EEPROM. Firstly, searching information from the web about a clear EEPROM data. Already bought a cheap EEPROM programmer and being shipped and see I can dump the data or not.

 

[BCX]

Might not even even need the eeprom programmer. The chip looks to use SPI, could get Arduino to dump out the contents.

 

[kc427]

Might not even even need the eeprom programmer. The chip looks to use SPI, could get Arduino to dump out the contents.

I used this cheap programmer to program my dash trip meter/odometer before with 93C46, and there is no problem on it.

 

[professor_jonny]

The RVR looks like it uses pin 12 for SRS comms from from 1999-1 to 2002-11 (I have the japaneese service manuals)
The RVR from 1997-11 to 1999-1 and from 2002-11 onwards I can't comment as I don't have those manual's and it may differ but from reading the russian manuals it looks like it on pin 7 from 2002-11 onwards is the same but the pictures are badly scanned.

I have brought a new srs module (well traded the old one) pluged it in and it works no faults now, A company offere a trade in program as it resets specific models, he said there is nomanufacture tools to reset crash datd but you can reset dtc's.
he said some are spi and some require sesoldering reporgramming.

My srs does not have a 8 pin eeprom it is embedded in the microcontroller unlike the above pictures.

 

[kc427]

The RVR looks like it uses pin 12 for SRS comms from from 1999-1 to 2002-11 (I have the japaneese service manuals)
The RVR from 1997-11 to 1999-1 and from 2002-11 onwards I can't comment as I don't have those manual's and it may differ but from reading the russian manuals it looks like it on pin 7 from 2002-11 onwards is the same but the pictures are badly scanned.

I have brought a new srs module (well traded the old one) pluged it in and it works no faults now, A company offere a trade in program as it resets specific models, he said there is nomanufacture tools to reset crash datd but you can reset dtc's.
he said some are spi and some require sesoldering reporgramming.

My srs does not have a 8 pin eeprom it is embedded in the microcontroller unlike the above pictures.

If doesn't have the eeprom, that would be much more complicated.