Posted By: Smitty
miprom 21 - 10/15/14 09:12 PM
I have a CPU that stops communicating to the service tool. In this case a genuine Mont.tool.
The tool works fine with the other units in the MR. I tried swapping the EE prom with intial success then failure.
The car will run but stops communicating with the tool. If you log out it cannot reestablish communication. This is particularly annoying after you inhibit the doors.I have tried two other CPUs. My next guess is the two static ram chips. I wouldn't think the board would work at all in this case. Any thoughts from you guys?
Posted By: Smitty
Re: miprom 21 - 10/16/14 10:04 PM
Got it. Issue with the power supply. I may have been picking up ripple on the 5volt. New power supply ie problem solved.
Posted By: Vatorgator
Re: miprom 21 - 10/18/14 03:22 AM
good find smitty, i was thinking about this last night, i have been checking on how the cpu communicates to the tool. the rj11 connector has 4 wires that are being unitized for communication, 2 of the wires go to 1 485 transceiver chip, and the other 2 wires go to another 485 transceiver chip. i was thinking the only thing that could be causing comm problems would be the 5 volt power supply to the chips, since you had changed out the cpu card. i have had 2 other people complain about this in the last 2 weeks, and you just happened to post this, thanks for the great post. I was wondering why the car would still run with no problems, but the communication would fail. seems that maybe the ripple is just enough to mess with the communication chips, and not with the other chips on the board. just thinking about why this would be, any thoughts
Posted By: Smitty
Re: miprom 21 - 10/21/14 01:41 AM
I was surprized that the culpret was the 5volt. Usually in comm circuits the +-12 is the problem.
Posted By: uppo72
Re: miprom 21 - 10/23/14 04:58 AM
good find smitty, i was thinking about this last night, i have been checking on how the cpu communicates to the tool. the rj11 connector has 4 wires that are being unitized for communication, 2 of the wires go to 1 485 transceiver chip, and the other 2 wires go to another 485 transceiver chip. i was thinking the only thing that could be causing comm problems would be the 5 volt power supply to the chips, since you had changed out the cpu card. i have had 2 other people complain about this in the last 2 weeks, and you just happened to post this, thanks for the great post. I was wondering why the car would still run with no problems, but the communication would fail. seems that maybe the ripple is just enough to mess with the communication chips, and not with the other chips on the board. just thinking about why this would be, any thoughts
Vator, can I ask I heard of a potential fault regarding communication between a drive and the controller via serial data errors. The manufacturer(European) aren't sure but our installation guys think the chips cant work fast enough for all changes of state. I read here that maybe the power supply isnt secure enough and that can maybe create a fault like a communication error. Can modern chips not operate fast enough and can it also be a supply error? thanks in advance mate.