When you look at the DIC what does it say under RTD? The connection I was talking about was a reference to the graphic for the switched power. But I fixed the graphic so disregard that. Sorry for the confusion. schematic shows the power to the ETC as well as relays and fuses in the underhood power center. Also location of the ground wire and where it grounds under the car. I would be curious if the issue was the TECH 2 by chance. I would want to connect to another car and see if it would work on it (another c5). Just to be sure it isn't the TECH 2. If not.. then check for power/ground on the connectors with a DVM.

Just throwing ideas out there to check. But really wondering what the DIC says under RTD. Codes/No codes. If not NO COMM, wondering if anything. Curious, since TECH 2 don't connect to module and not a no comm error in DIC.

 

DIC says under RTD no codes...wonder if that is due for the same reason the TECH 2 cannot connect. Question...since/if DIC and tech cannot connect....what is putting the message on the DIC panel. How does it know to display the message. could not sleep...mind too busy.

 

Check other codes. Any Uxxxx codes in the car. For instance, Under IPC code U1056 is loss of communication with RTD. That would show the IPC DIC can't talk to it just like the TECH 2 isn't. Good luck getting to sleep.

 

Fresh morning, so just want to recap where I am with this challange.
1 I get the message "shocks inoperative, max speed 80 mph"

2 went thru the DIC IP and checked codes....none found!

3 hooked up recently obtained TECH 2 to identify issues and checked car for DTC's..none also found

4 I could access all TECH 2 areas ok until I got to the CHASSIS CVRTD screen saying "establishing communication" at which time I get a micro second blip of screen data then the TECH 2 shows "no communication" (key ON/OFF)

5 took the TECH 2 to my 94 coupe and verified that the instrument could read all areas and screens thereby pointing me to the 97 and the chassis section to troubleshoot.

6 today will look at ground connections...especially those two closest to the ESC moudle in the rear LH Trunk area.(I have in the past gone thru all the grounds per forum member B. Curlee's findings and posts.) May be time to revisit them after 14 yrs.

7 ESC module removed and connections verifies as nice and clean, no loose wires or pins.

8 pulled the RTD relay in the fuse box, engine compartment, ohmed the relay @ 86.6 ohms and verified contact N.O. were N.O. (will attempt today to hook up volt meter to the RTD relay when accessing with the Tech 2 to see if the relay is actually functioning under loaded conditions. (not sure WHEN or HOW this relay becomes energized or under what conditions...maybe during selector switch activation, load changes in travel ??) ANYONE have insight on this.(more FSM reading to do this weekend)

9 QUESTION unclear to me how or what I mean here but wonder how the serial bus data line, RTD relay, and Tech 2 interrogation sequence correlate with this problem. need to understand the schematic control sequence of signal travel. since modules talk to each other on the same bus...could another one be interfering...I BELIEVE BECAUSE I SEE THE MICRO SECOND FLASH OF THE CHASSIS DATA SCREEN BEFORE IT GOES TO NO COMM that the SERIAL BUS COMMUNICATION line is good.....then what is disrupting that com link. (not much sleep last night with all this swirling in my head)

ok, guess thats about it as a summary...today put it up on blocks, check grounds, check if ESC in 94 is same as ESC in 97 for comparison, figure a way to see RTD become energized with volt meter when using Tech 2..if applicable.

 

With No Comm you will not throw any codes since they can't be communicated. I am surprised the DIC does not show No Comm for the ESC when you look for codes. However the DIC message you get from via the BCM clearly says it cannot communicate with the ESC. The BCM is the "traffic cop" module that requests the "Health" of each module in an ongoing basis.

If you need help with the schematics let me know. Not at home to tell you when the ESC gets powered. At minimum it has to be ignition ON and engine running.

I would be verifying ESC power and ground. I would also check continuity on the serial bus from the ESC to the Star connector.

Not sure if the "flash" you are seeing is internal to the Tech 2 in trying to display a screen selection just prior to communicating to the module via the serial bus . A No Comm should override that screen very quickly.

I think your Tech 2 is fine.


Mr. Sam

 

Well, review the private message link.

happy it is working, unhappy no definitive solution was identified as of this point. no change with volt meter disconnected.

working on the grounds just to be sure, looking at possible wire issue in ESC connection both in the trunk and at the underneath connector of trunk.

Cannot imagine the $$$$ if at a dealership for the time I have spent. I am around 40-50 total time spent over the past 3 weeks working this challenge.

break time, be back later with any findings

 

I'm confused////,,,, Is it working???

I was going to provide some suggestions.... DO you have power to the fuses to the ESC Module when the KEY IS ON and if so,,,, is it full battery voltage?

If the Hot in RUN & START fuse isn't getting voltage with the key ON,, you will get NO COMMS and the same as if the ground or Hot at all times was bad.

Those things MUST be checked and established FIRST any time you have any failure.

A couple more things..

Your C4 is an OBD 1 car. Not the same as the OBD 2 system..

If it were my car,,, the F-45 suspension would have been gone a LOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO OOOOOOOOOOOOOOOOOOOOOOOOOONG time ago.

Until you drive a properly designed purposed installed suspension, (i.e. Z-51, ZO6 or any aftermarket suspension), you DO NOT know what you are missing in performance handling.

I had an F-45 equipped 98 Coupe. I HATED every thing about its handling. A COMPLETE waste of $1500 option money!


In your car, if you JUST change the shocks to C6 ZO6 shocks,, you will be absolutely AMAZED at the difference in handling. Your 100,000 mile shocks are completely useless by now as all the pressure is gone in each shock and the dampening is all but minimal if any exist. Been Thur this on several car with your age/miles.

Just disconnect one end of one shock and exercise it FULLY EXTENDED/FULLY COMPRESSED. See how much dampening you have.

BC

 

Yes Bill, as of now it is working. Unclear as to WHY but left the ESC out all night, reinstalled this a.m. see earlier post.

 

The meter is measuring the coil and it did change voltage state. But you are correct it may have altered the circuit just enough....That's why others looking at a challenge is just good business.

I will go out and do the contacts today.

Question.....with the meter off and if it was an alternate path...now that the meter is not in the path....access is still available....which would lead me to believe the contacts are closing. still unclear as to what the initial issue for no comm would have been unless it was the ESC. I did not see a RTD relay part number but did find a relay for the fuel listed at a local parts house.

ok, the contacts are working, voltage drop with relay N.O., coil activated and voltage = zero. screen access ok with just the tech 2 connected and able to run diagnostics.

Question.....wonder if the movement of the fuse box pulling and replacing the relay is the fix, the grounds did not get done until after it was able to read the chassis....just more things to ponder.

again, thanks for sticking with me...still foggy so have not road tested.