I forgot one line.
Also send this before the others.
AT H1
This command "AT H1" turns on the headers
NEED HELP Unknown Driver and No Start
- Thread starter Mramses
- Start date
I forgot one line.
Also send this before the others.
AT H1
This command "AT H1" turns on the headers
If the PCM I'm testing was not the one in the truck, should it still turn on? without programming?
I do not understand why the anti-theft light does not appear if it is the PCM of another friend truck?
I do not understand why the anti-theft light does not appear if it is the PCM of another friend truck?
If there is a communications problem in the instrument panel the security light as well as many other functions of the instrument cluster will not light or work.
Show us the results of sending to the elm327....
AT H1
AT S1
AT SH 6C FE F1
20
@Mramses
I made a video to show you that communications is mandatory for the security light to light up. The PCM can not light the security light, or the PRND321 status, or the oil pressure, or the engine temperature unless the instrument cluster is communicating. You may have an instrument cluster problem. Maybe you still need a "security relearn" and we cannot tell that because the instrument cluster is bad??
Your last test with the elm327 looked better than the first. But the "AT 10" command was wrong and that is why it replied "?".
Here I light the security light using my phone and sending the command myself.
I made a video to show you that communications is mandatory for the security light to light up. The PCM can not light the security light, or the PRND321 status, or the oil pressure, or the engine temperature unless the instrument cluster is communicating. You may have an instrument cluster problem. Maybe you still need a "security relearn" and we cannot tell that because the instrument cluster is bad??
Your last test with the elm327 looked better than the first. But the "AT 10" command was wrong and that is why it replied "?".
Here I light the security light using my phone and sending the command myself.
The results you sent most recently have the wrong commands. I do not see results of these commands following here....
AT H1
AT S1
AT SH 6C FE F1
20
These are the results I need. Not "AT 10"
You are so close!! Almost right. The "20" needs to be on a separate line by itself, after the AT SH 6C FE F1.
Disconnect the cluster wire from G.
The ISO 9141-2 is not the right protocol so we must again set the right protocol. Add the AT SP 2 before the AT SH 6C FE F1.
So send it EXACTLY like what you see here. Each line as it shows here.
AT SP 2
AT H1
AT S1
AT SH 6C FE F1
20
I know this is frustrating. Try sending the " 20" a second and maybe third time. Sometimes the network doesn't wake up the first time. Also, try with the jumper from purple to blue/white and no jumper to PCM or BCM, only purple to blue/white. Send same commands as you last sent.
should i connect the comb sp 306? because I have it disconnected.
help me friend I do not understand why we do not find changes or signs of life
Here I will explain what you are sending so you may know.
AT H1 means the elm is to include the message header in the responses. Elm default is to not show the headers but we need to see headers. Each message has a 3 byte header that defines what type of message, who is the message for, and who is sending the message.
AT S1 means to print a space between the pieces of the message. This just makes it easier tonread the separate bytes of response messages.
AT SH 6C FE F1
means the elm is to set the header for our messages to be sent. Here we define the type of message, who our messages are sent to, and who are we that is sending the message. The "6C" and "FE" means we are sending a message for any module on the network to respond to if they recieve it. The " F1" is the network address of the ELM327.
The " 20" is a call for any module operating on the serial data line to answer
AT H1 means the elm is to include the message header in the responses. Elm default is to not show the headers but we need to see headers. Each message has a 3 byte header that defines what type of message, who is the message for, and who is sending the message.
AT S1 means to print a space between the pieces of the message. This just makes it easier tonread the separate bytes of response messages.
AT SH 6C FE F1
means the elm is to set the header for our messages to be sent. Here we define the type of message, who our messages are sent to, and who are we that is sending the message. The "6C" and "FE" means we are sending a message for any module on the network to respond to if they recieve it. The " F1" is the network address of the ELM327.
The " 20" is a call for any module operating on the serial data line to answer
The commands you sending are correct. Most of the modules on the rear splice pack are door and endgate modules. You previously stated the doors do not work. I would keep trying other modules looking for an answer from one of them. Try the TCCM next on terminal C, dark green/white wire.
Truly, I do not understand. There should be a response. I have been reviewing your tests and pictures. Are we certain the purple wire has continuity? The elm needs only power and the purple wire to pin #2 of the 16 pin OBD connector. We know elm has power. If there was a break in the purple wire we would get these same results, but I believe you have checked this purple wire thoroughly.
This from my vehicle purple wire jumpered to dark green/white TCCM.
Edited: The last blue line in the image is an answer from the TCCM.
Attachments
I have seen where you typed in " ATZ" and one answered 1.5 and another answered 2.1.
There have been reports I have read from some users that newer ELM copies no longer support our old trucks that use SAE J1850 VPW. These users have been unable to connect to our old trucks. I would check again with ATZ. I suspect the 1.5 version to be a better choice.
Edit: try both
I am puzzled. Only other test I can come up with is to try the PCM alone. To do this would require jumper from purple to PCM dark green and disconnect the connectors at the BCM to isolate the yellow wire between PCM and BCM.
What is the history of the truck. Did it run OK before the engine work? Did something else happen to it that might have caused electrical damages?
I can think of no reason that none of the modules respond to the elm devices.
What is the history of the truck. Did it run OK before the engine work? Did something else happen to it that might have caused electrical damages?
I can think of no reason that none of the modules respond to the elm devices.
Perhaps the issues involved here concerns the "Ground" Side of these Front Cabin Data Bus and IPC Class 2 Connections. Check out @!MAY03LT 's interesting explanation regarding the Common Grounds connected at G201 and SP201 in this Video. Practically all of the issues regarding the Instrument Panel Cluster and many other Modules need a Solid Ground Connection made there with an Extra "Toothy" *** Star*** Washer:
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I think it is not the same year. but trust me for having only the same connectors. that is not the same year influences?
Hello friend, what tests are we going to perform? If a module has power, ground and data line, can it communicate with it?
should elm read it?
For example, if the pcm is given the 4 power and ground, should it have communication? without being connected to the branch of the truck
We have tried to communicate with many modules but have no success. Our elm commands are correct. It is unlikely that so many modules could all suffer bad grounds or lacking power. The Chinese copies of the ELM are known to be sometimes of inadequate construction, lacking some features. You could try to confirm that the elm are sending signals by connecting the meter to the purple wire and ground, connect no jumpers, just the elm connected to the meter. Set the meter to a low setting of say 2 volts. Use the car scanner terminal as you did yesterday. There should be a very brief change in volts when you send the "20" . There will be no change in voltage when sending any line that starts with "AT". Also no change whenever the elm replies "?"
A valid point for certain, but yesterday we failed to communicate with modules whose grounds are not at all common. They varied from the under dash to the engine compartment as well as back at the D pillar and also one module whose ground is through its case through the mounts. Seems unlikely to have so many failed ground sources. Unless there were issues with a primary ground connection from the battery to the chassis. But the DLC itself grounds through one of these common ground points, G201, and I wouldnexpect the ELM unit itself to suffer power interruption issues if that ground was faulty.
I do not know if a PCM will communicate outside of a vehicle. I do know that the PCM requires only pins C1-20 and C1-21 to be powered to enable communications. Pins C3-17 and C1-19 don't get powered until the RUN position and this video shows PCM messages as soon as the key moves, even before the ACCESSORY position. Watch for the green messages to start moving.
Not sure if I can provide any further help BUT... more reading of the SI and hopefully learning something. The SI indicates that you need to ensure that you can communicate with the BCM as the BCM sends out a "power mode / wake up" message on the DLC to cause things to start "talking". Hence, all the nice testing with terminal session needs to focus on trying to talk to the BCM. Of course, to ensure that it can work, you need to ensure that electrically it is properly connected so you need to check voltage and grounds along with ensuring that the data bus that it is connected to does not have either a short to ground and voltage. Sorry for the side track if this doesn't help.
Here is a good video explaining in detail how the data and modules work. I would suggest for the OP to make sure his tools are working. First make sure he can use his App and ELM327 on another car to verify that he can use it to communicate with the car first. Once that is done come back to the problem car and try to communicate, if he can't then do the following. Taken off the "combs" and try again. If he still can't communicate start by checking the positive, negative and the data wire to the OBD2/ALDL. With the combs removed must modules should be off line. That only leaves the wires integrity to deal with. Its highly unlikely that all the modules took a dump at the same time. Try to take everything off the data lines and then bring one item at the time. This was told to him many times and he keeps reporting back that he still can't communicate. That leads me to believe its either his tool or the data lines themselves. Can he disconnect the Instrument Cluster to see it that helps with the communication issue?
He needs to communicate with at least one module to be able to find the bad module, if there is one. I would concentrate my time on checking and re checking first my scan tool then the data line. He said the Tech2 couldn't communicate, so that's 2 tools that won't communicate. That again leads me to believe it is a problem with the data line, power, grounds, wire integrity. Cut line, pinched, rubbed through some how compromised. Do a real good visual on the line from the OBD2 connector to wherever it leads to. Hope this helps.
On a side note you guys on this forum are awesome for all the help you have offered.
He needs to communicate with at least one module to be able to find the bad module, if there is one. I would concentrate my time on checking and re checking first my scan tool then the data line. He said the Tech2 couldn't communicate, so that's 2 tools that won't communicate. That again leads me to believe it is a problem with the data line, power, grounds, wire integrity. Cut line, pinched, rubbed through some how compromised. Do a real good visual on the line from the OBD2 connector to wherever it leads to. Hope this helps.
On a side note you guys on this forum are awesome for all the help you have offered.