Sys, and battery drain, FX3 questions

[Paul Higg]

Okay, did the SYS light start flashing only after you had the CD changer installed? If so I can help you with the wiring diagrams. The CCM is real fickle when it sees an open line in it's circuit.

If it did NOT come on immediately after the CD changer installation then it could be some other fault. There's a whole boat-load of stuff that could throw a SYS light.

 

[JAKE]

You could also try disconnecting ALL the CD changer wires to see if that cures the SYS light.

Jake

 

[qblue90]

Hi Paul

The SYS light did come on after I installed the Changer, but I do not recall if it were immediately after. I do have something else going on with the radio as both left side speakers make a horrible noise. Im thinking the amps are blown. So I have them unplugged right now. I posted above that last night I swapped the left and right rear speakers to see if the issue with the left would follow. It did and now my right rear speaker dosent work. I have no idea why it dosent work now. All I did was unplug it to test the left speaker and then plugged it back in..

Hi Jake-
To touch on what you stated, which was to disconnect the CD changer completely... I originally thought that also, but now I think I have other audio issues that will make the SYS light continue until they are repaired. If my amps are bad, or the speakers are unplugged, which the left side is because of the horrible noise they make, would that trigger the SYS light? I will still try to get that changer disconnected. One less variable out of the way till I figure everything else out. Why the heck would my right rear speaker stop working from unplugging it and plugging it back in? Grrrrr. I am so depressed over this now...

Thanks for the help guy. I am bumming.
Kev

 

[qblue90]

Can someone tell me what the C41 code means? Please.

Kev

 

[Paul Higg]

Kev, according to my 94 FSM a C41 means ("C") is current, PCM/ECM serial Data Circuit. Loss of communications.

"DTC 41 will set when: The CCM (Central Control Module) is the master of the bus and the PCM (Powertrain Control Module (VIN P)) (LT1) or the ECM (Engine Control Module) (LT5) does not respond to three CCM polls."

"Sets a DTC 41 and flashes the SYS indicator." I have a troubleshooting page I can scan and send to you via e-mail as a JPEG if you'd like.

Paul

pjhigg@comcast.net

 

[Paul Higg]

Hi Paul

The SYS light did come on after I installed the Changer, but I do not recall if it were immediately after. I do have something else going on with the radio as both left side speakers make a horrible noise. Im thinking the amps are blown. So I have them unplugged right now. I posted above that last night I swapped the left and right rear speakers to see if the issue with the left would follow. It did and now my right rear speaker dosent work. I have no idea why it dosent work now. All I did was unplug it to test the left speaker and then plugged it back in..

Hi Jake-
To touch on what you stated, which was to disconnect the CD changer completely... I originally thought that also, but now I think I have other audio issues that will make the SYS light continue until they are repaired. If my amps are bad, or the speakers are unplugged, which the left side is because of the horrible noise they make, would that trigger the SYS light? I will still try to get that changer disconnected. One less variable out of the way till I figure everything else out. Why the heck would my right rear speaker stop working from unplugging it and plugging it back in? Grrrrr. I am so depressed over this now...

Thanks for the help guy. I am bumming.
Kev

There is a possibility you may have fried your stereo amp unit located under the rear access panel inside the car. Did you do this with the fuse in? Did you since check all the fuses?

 

[Hib Halverson]

I can't explain why codes are set with the service light on, other than it is possible, a fried controller or a problem with the controller connector is the problem. Again, clear codes, check the connnector at the SRC module then road test.

As for clearing codes in the SRC controller, the statement was made earlier that one can do this by disconnecting the battery.

Not.

With SRC, to clear codes, turn the key on with engine off, then ground pin "C" of the DLC for two seconds. Do that three times in succession.

As for your "SYS" warning, you mentioned earlier that both a current and history DTC41 were set in the CCM. I don't know what all this talk about the entertainment system and the light sensor is about because, if the CCM has DTC41 stored, that is a fault with the serial data communication between the CCM and the ECM.

Again, I'd clear codes and road test. To clear CCM codes, with the ign. off, ground pin G of the DLC. Turn the key on but don't start the engine. Press the Trip/Odo button on the DIC until 1.7 shows in the IP display. Press the Eng/Met button and that will clear codes. Cycle the ign and verify the codes are cleared. Turn off the ign and remove the DLC wire.

I don't have time or the energy to key-in all the diagnostics for DTC41, but after reading it, I think the first thing I'd do is get your FSM, then trace down all the circuits listed in the solution for DTC41. If you can repair that, I'd clear the CCM codes and the SRC codes and road test.

Is the ABS service light on in this car or has it been recently?

Lastly, when you key up, does the service ride control light come on during the bulb check?

 

[Paul Higg]

Hib, if you'd take the time to look for the thread about the SYS light and the radio mod with the resistor you'd understand. My first question was did he install a new stereo because that WILL set a SYS light, AND the ambient light sensor IS involved with it.

 

[Hib Halverson]

I understand that, but if the "SYS" warning is showing and their are CCM codes set (ie: the H41 and C41) then, in my opinion, it's advisable to solve those problems first.

It is possible the stereo and the ambient sensor can turn on the SYS warning, as well, but they may or may not be doing it in this case.

Bottom line, diagnose the DTC41 first. Solve it. Clear codes, then road test.

 

[Paul Higg]

I can agree with that.

 

[qblue90]

check the connnector at the SRC module then road test

With SRC, to clear codes, turn the key on with engine off, then ground pin "C" of the DLC for two seconds. Do that three times in succession.

As for your "SYS" warning, you mentioned earlier that both a current and history DTC41 were set in the CCM. I don't know what all this talk about the entertainment system and the light sensor is about because, if the CCM has DTC41 stored, that is a fault with the serial data communication between the CCM and the ECM.

Again, I'd clear codes and road test. To clear CCM codes, with the ign. off, ground pin G of the DLC. Turn the key on but don't start the engine. Press the Trip/Odo button on the DIC until 1.7 shows in the IP display. Press the Eng/Met button and that will clear codes. Cycle the ign and verify the codes are cleared. Turn off the ign and remove the DLC wire.


Is the ABS service light on in this car or has it been recently?

Lastly, when you key up, does the service ride control light come on during the bulb check?

Thanks Paul and Hib. I appreciate all the help. I am confused about clearing the SRC codes.... What do I ground pin "C" to exactly? Pin "A" again? Should I have the key in the "ON" position already and leave it there then ground "C" 3x? Just need a little clairification on this process please.

How do I verify connection at the SRC module? Really what I need is where do I find the SRC module?

The ABS light has never been on.

Yes the Service Ride Control light does come on during the bulb check.

I did recheck the codes after I tried to clear them by disconnecting the Neg cable... Obviously I still got the same codes as they were not cleared, however one thing did change on the CCM side. I still got the C41 and H41 codes for Module 1. Module 4 reported Err this time(which I assume means ERROR). Does this point me in any particulair direction?

 

[qblue90]

Need help clearing codes

Ok so here is what Ive done...

With the key in the "ON" position, I grounded pin "C" to pin "A" for 2 seconds 3 consecutive times. That was a success. My SRC light only binks 12.


The CCM codes are another story...

Once again the key is in the "ON" position. I grounded pin "G" to pin "A". I pressed the Trip/Odo button until I saw 1.7
I pressed the Eng/Met button and saw --- on the display. I could not get anything else at this point.
I cycled the key and..
Module 1 still reports C41 and H41
Module 4 still reports Err

I tried several times to clear these codes using this process without success. After Ive attempted to clear the codes, the SYS is back on as soon as I cycle the key. What am I doing wrong?

Kevin

 

[Paul Higg]

Kevin, it looks like you're doing everything correctly. First, the DTC 41 we covered when I sent you the page. The C means it is current and H means it is a history code. So you definitely have a problem there. The three dashes are a good thing. It means it didn't find any faults in that particular module.

Module 4 is the PCM/ECM (Powertrain Control Module), (Engine Control Module). As for the Err, the FSM has this to say about it, "If there is a communications problem between the PCM/ECM, EBTCM, or DERM and the CCM, the speedometer will display "err" when the CCM is trying to communicate with the modules." So, it looks like a communications problem between PCM/ECM and the CCM (Central Control Module) which would be in line with the DTC 41 Loss Of Communications.

Did you do as Hib suggested and reseat the connectors? Did you look for corrosion? Bent pins?

You may even have an open or an intermittent open. You will have to do some serious work with a meter. One word of advice though, when you are looking for an open line, when you check pins of a plug make SURE the other end is disconnected from the component because you are sending voltage through the wire from the meter. Since you are an engineer you probably know how to "ring" wires anyway. I just wanted to throw that in there because ringing wires with a meter can fry computer boards if they are not disconnected. To properly check a wire you'd disconnect both ends of the wire, (the plugs), then put one lead on the pin of one plug and the other meter lead on the pin on the other end of the harness in the other plug. If you have continuity it is good, providing you do not also have continuity to ground. If you do then you have a short somewhere.

 

[ecss]

Try pulling ECM codes direct from the ECM and not thru the CCM.

Short Pin A to Pin B and turn the ignition ON.

Look at the service engine soon lamp.

Code 12 will blink 3 times then any error codes if there are any, then code 12 three more times at the end. All codes are two digits.

Example code 12 is blink pause blink blink longer pause.

If you can't get the ECM to display DTC codes the ECM is most likely bad.
You can try reseating the RED connector at the ECM. One of the pins on the RED connector is the serial data bus which is the communication line between the CCM and ECM.

Make sure you disconnect the battery if you reseat the connector.

Also note when you short Pin A to Pin B, the fans will run and you'll hear a clicking noise which is the IAC being forced closed that's all normal.

If you can pull codes from the ECM, I'd due as suggested and look at the CD installation.

 

[Paul Higg]

Hey eccs, good post! I didn't know that. I'm going to add that to my list of saved posts!

 

[Hib Halverson]

Ok so here is what Ive done...

With the key in the "ON" position, I grounded pin "C" to pin "A" for 2 seconds 3 consecutive times. That was a success. My SRC light only binks 12.


The CCM codes are another story...

Once again the key is in the "ON" position. I grounded pin "G" to pin "A". I pressed the Trip/Odo button until I saw 1.7
I pressed the Eng/Met button and saw --- on the display. I could not get anything else at this point.
I cycled the key and..
Module 1 still reports C41 and H41
Module 4 still reports Err

I tried several times to clear these codes using this process without success. After Ive attempted to clear the codes, the SYS is back on as soon as I cycle the key. What am I doing wrong?

Kevin

You're not doing anything wrong. You can't clear the codes because there is an ongoing problem with that system. The C41 and the H41 have already been explained.

The "Err" in module 4 means...(well duh!!!)...there's an error because of the problem in the serial data line running between the ECM, CCM and the EBM. The ECM can't send data to the CCM to put up on the IPC!!!

Buy the service manual, consult the section on CCM and follow the diagnostic and service instructions for CCM DTC41. Expect to either repair a wiring problem somewhere or buy a new CCM.

As for why SRC blew all those codes?
Search me.
But, don't look a gift horse in the mouth as your Selective Ride seems to be ok.

 

[Paul Higg]

Kevin, see if someone can send you the same pages I sent you for your year and see if they match, then follow the troubleshooting steps and you should be able to find the problem.

 

[qblue90]

An update on the issues and a question for Hib

Hi guys!

Just thought I would bring the thread up to speed with the issues my car is having.

Issue 1. Speakers in Delco Bose Gold squealing/not working... It turns out all my amplifiers were bad. In fact.. the front right speaker amp had experienced a "thermal event". It looked like it had gotten wet somehow at one time as the metal cover over the amp was covered with rust. Anyway, I sent all the amps to Doctor Don's and they did a fantastic job! Got the amps back in a week and now my radio is rockin again. If you have amplifier woes, I suggest Doctor Don's. Great Job!!!

Issue 2. SYS flashing. This is still happening. I still have the C41 and H41 code. I did do as Eccs suggested and tried to pull codes directly from the ECM and was successful. There were not any codes in the ECM. This error is not effecting driveability one bit, so I'm driving and enjoying my car and will worry about it this winter. I do have my FSM finally so Im not really that worried about it. When I do fix it I will update the thread with results.


Issue 3. Battery Drain... I just replaced my battery with another Die Hard gold. The battery had gone completely dead over the winter when I needed my charger for other reasons, and we all know what a bad thing a completely dead batter is. The battery would no longer hold a charge. This is probably the fifth battery I've put in the car so there is something going on here. As long as I drive the car on a regular basis its ok so thats what Im doing. This will be another winter project and I will update the thread when (if) I figure it out. I'm sure this will be a challenge.


Issue 4. FX3... Shocks feel softer than they did. Here is my question for Hib.

Hib, earlier in this thread you stated:

I will offer some guideance on the problems with SRC. Let me preface this by telling you that your car sometimes may "feel soft" because it is soft. In 89 and 90, all cars which were ordered with both Z51 and FX3 were downgraded to the base springs and stab. bars. The downgrade is not widely known, even today, and back in 89-90 Chevrolet did not make its existence known to the public.


My question on this is that my car has the Z51 and FX3 and the FE7 and J55 RPO's. If my car has the FE7 RPO, then did the suspension still get downgraded? I would really hope not as Heavy Duty Suspension is checked off on the sheet. I'll be pissed if we didnt get it. Is there a way to verify if I did or did not get the HD suspension? My car dosent feel soft, just not as stiff as it used to be. The car's getting old, just like me !! The shocks show no sign of leakage. They are going back to Bilstein for a rebuild this winter. The question... did I get FE7 and how do I tell? Stab. bar diameter perhaps?

This car rocks with the 6 spd and 3.33 rear end.

Thanks for all the help guys.. I will update the thread as I fix things!

P.S. I just replaced my Firehawk SZ 50's that I put on in 2001 with GS-D3's.. Man these tires are pissed off!!! Very agressive looking. Very agressive on my wallet too. I will need more seat time to evaluate them but so far, I think I like them. I believe the new sticky rubber might be accentuating the fact that my shocks arent as stiff as they used to be. Feels a little strange diving into corners really hard.

Thanks again and Save the Wave!

 

[qblue90]

Update July 2015 to SYS

Hello CAC!

I thought it was about time that I updated this thread. Our 90 has 55K miles on her now and has developed some drivability issues. Once we brought her out of storage this spring we quickly discovered that the alternator was not doing it's job and had to be replaced. After that all seemed fine. Then it suddenly ran poorly while my wife and I were cruising. Started missing. We had been running the AC. We parked it and had dinner. After dinner, we drove the car straight home with running the AC. All seemed fine. The car sat in the garage all week until my wife took it grocery shopping. She drove all afternoon without and issue. As she was driving home, she used the AC (she had gotten ice cream) and the car started running poorly again within approximately 3-4 miles. If died on her. When I got to her I checked batter voltage and it was 12.6. She said the gauge did not indicate anything overly hot, and I know the gauge is not very accurate. It started right back up and I was able to drive it the mile back home without any other incident.

Also of note, this whole time that we had been driving it, it would leak about a volley ball size puddle of coolant on my garage floor. Right under the middle of the front of the engine. I could not see where any leak was coming from, but I assumed that the water pump was going bad.

So here is what I have done so far and the results:

I pressure tested the coolant system and found no leaks at all. So I thought that maybe my fans were not working properly. I ended up getting an ALDL cable and used some software off the net to monitor data. My car has two electric fans. The fan on the RH side does not always seem to come on. Even if I jumper pins A&B of the ALDL. The connections at the fans are good and the relays seem to be good. I verified this by switching the connectors at the fans and then switching the connectors at the Relays. Still got the same results. The RH fan only seemed to come on intermittently. My software did tell me that the LH fan was coming on at 109 C or approx. 226 F and off at 104 C 219? F. When I turn on the AC, both fans come on. Otherwise it seems only the LH does. Is that normal operation? I have no explanation for the occasional puddle of coolant. Fuses and wiring to the fans are all fine also.

disconnected the software because it did not have the ability to pull codes that I could find. I ground pins A&G of the ALDL to access the CCM. The CCM gave me C41 and H41 as it has for years now. When it switched to module 4 it gave me (---) which I thought was odd. Because it has always given me Err in the past. This was the SYS flashing where my Instant Average used to be.

I ground pins A&B to directly access the ECM codes. I got codes 41 and 51. I ground pins A&G again and went to 1.7 to erase the codes. The CCM still reported C41 immediately and this time also resumed the Err when it switched to module 4 (ECM). I jumped A&B and still had DTC 41 and 51. They had not erased. I disconnected battery negative. Then the ECM codes were gone. I did not drive the vehicle.

I then went after the CCM code 41. With battery disconnected I located the Red connector at the ECM with the two wires for the CCM. I disconnected it and dug out the CCM. I disconnected the CCM and checked both wires per the FSM for short to ground, short to power and open circuit. There were no issues with the tan wires.

I removed and reseated the PROM. Nothing appeared to be out of the ordinary with the PROM or the connections. Nothing was out of the ordinary with the Red connector or the connectors at the CCM. I reseated all the connectors at the ECM and put the car back together.

When I started the car, the SYS was immediately back. I jumped A&G and got C41 and H41 still and Err on 4. The ECM reported no codes. Please keep in mind that up to this point my Service Engine Soon light has never come on. And yes it works during the bulb test.

It seemed to be running fine, so I drove it. Immediately once I got rolling the SYS vanished and my Instant Average started working again! I was hopeful... After approx. 4 miles my Instant Average locked up at 69 and the SYS started back up. At almost the same time, the engine started running poorly again and the Service Engine Soon came on. The car was missing. The SES went out after about 10 seconds and the car started running normally again. Still had the SYS of course.

Checking the ECM DTC's once I got home got me a DTC33 from pins A&B. Never had that before. I disconnected the battery and reseated all of the connectors at the ECM again. I found nothing strange with any. I started the car but did not drive it. The DTC 33 was gone. I thought maybe a tune up is in order. It has been approx. 20K miles since I've done that. I replaced the cap and rotor but left the same plugs and wires. As soon as I started it up it was missing badly and stinking up the garage. The Service Engine light comes on instantly and stays on.

Now when I ground pins A&B my Service Engine Soon light does not flash codes. It just stays on constantly. The ECM is not talking. I can still jump pins A&G and I still get codes C41 and H41 and Err on Mod 4.

Does anyone have any idea's? I think my ECM is toast, but the only way to verify is with a "known good".

I intend to check all the grounds this weekend, but my spidey senses tell me they will be fine and won't fix anything...

I appreciate any advice as always...

 

[qblue90]

It was a bad ECM this whole time. Ordered a remanufactured ECM and it has cured all the issues. No more SYS. She runs well again. Thanks to all on CAC for your help!