FX3 troubleshooting

[Coupe de jour]

I have been troubleshooting a right front problem on my 91. I had a right front out of position fault originally. I found a broken adjuster on the right front shock.

I recently had all the shocks replaced and the light went out initially. On the drive home I was trying out the different switch settings. No problem on touring or sport modes but when I went to performance mode the light came back on. *&^%$#@! This time it was code 14, right front time out.

I discovered that the actuator on the right front was only cycling intermittently so I swapped it with the left front actuator. The problem remained in the right front so it is not the actuator. I made the following checks per the manual.

Voltage:
"E" to GND = 5.03V
"E" to "A" = 4.97V
"D" to "A" = 4.97V
these measurements were good according to the book.

Resistance on right front:
"B" to GND = 3.4M ohm
"C" to GND = 3.4M ohm

I also checked the resistance on the left front for comparison since there was no value given in the book:
"B" to GND = 2.7M ohm
"C" to GND = 2.7M ohm

There were no open lines or shorts to ground.

Has anyone had intermittent operating conditions? The dealer want $1700 for a new ride control computer. I'm hoping I have a wiring problem instead.

Thanks,
Kurt

 

[e3imcba]

HI, Kurt! I stumbled across your thread while searching for diagnostic codes for my FX-3. After having had all 4 shocks rebuilt by Bilstein and replacing one actuator with a used unit, my FX-3 system on my '92 finally worked well - most of the time - until yesterday. Now the light stays on, and it's reading codes 13 & 14. Can you tell me what these codes are? Also, if you should need a Bilstein computer, I can give you the e-mail address of a guy who recently replaced his shocks with standard Bilsteins and may be happy to sell his computer. Good luck, and let me hear from you! - John A.

 

[e3imcba]

Hi again, Kurt. I saw in your thread that code 14 is right front time out - I missed that in the first reading. Since my problem was intermittant, I suspected poor electrical connections, so I sprayed them all with contact cleaner and lightly coated all pins (actuators and computer) with dielectric silicone grease for improved performance and protection. That's when my problem went from "occasionally" to "permanently" ...Go figure. At any rate, there's always a solution - somewhere. __ John

 

[Coupe de jour]

Hi John,

First of all the fault codes which I assume are the same as my '91:

13 = Left rear time out
14 = Right front time out

One of the things I did to eliminate possible failure modes was to swap out the motor being reported as defective by the computer with a known good one. In my case I swapped the right and left front motors. I was able to eliminate the motor as the failure mode because I got the same fault codes even with the new motor installed. Doing that on the rear will be harder but still a good data point.

I highly recommend getting the factory service manual and electrical diagnosis supplement. They have been life savers for me since the car has so many electronic systems and corresponding computers. They also contain wiring diagrams so you can checkout the harnesses from end to end with a multimeter. I also did this and was able to eliminate the harness as a failure mode.

Finally, it is easy to get to the computer. Its under the storage bin behind the drivers seat. One screw holds the box to the trans tunnel. Unplug the computer and remove the screw. After removing the computer assembly, you should be able to open the plastic box that houses the circuit card. I inspected mine for any obvious signs of damage like broken or burnt components or bad solder joints. Sometimes you can get lucky and actually see the failed part on a circuit board. Read some of the previous posts on this thread and you will find the contact information for Bilstein. They can hook you up with a new computer with removable chips so you can change the programming of you suspension to anything from mild to wild. Cost of the computer with the chip of your choice is $241 which is about $1500 less than the dealer wants for one. I'm getting one and will soon know if that was my problem.

Good luck and let us know how you make out.

Kurt

 

[Hib Halverson]

My guess is the problems discussed, here, are not electric or electronic.

A time-out error means the shock absorber is not responding within the time programmed for bypass valve movement. If you get a time-out and the actuator is functioning properly, the problem is usually with the shock absorber itself.

My experience in servicing SRC (Selective Ride Control or FX3) is that when the shocks are overhauled by Bilstein (and this also may apply to new shocks), the new bypass valve shaft seals are quite stiff...stiff enough, in some cases, to slow bypass valve movement so much, the controler sets a time-out fault.

I've had this happen in two different cases where I have had front shocks overhauled. My solution was to clear codes and continue to drive the car. In a matter of days or a couple of weeks, nomal SRC operation resumed. Of course, if the problem continues for a while, then you assume there is a problem and begine the troubleshooting process for DTC13 or 14, again.

Now, there are a few additional talking points, here.
1) if you start the car 3 or more times without moving the vehicle, the Serive Ride Control light will come on.
2) If you have Bilstein overhaul a set of 80-91 shocks and also have them update the shocks to the 92-95 specs, you also MUST change the SRC controller to the later model type.
3) I advise against beginning an SRC troubleshooting session without the factory service manual.

More information on service of the SRC system is at:
http://forums.corvetteforum.com/reviewpost/showproduct.php?product=301&sort=7&cat=7&page=1
http://www.corvetteactioncenter.com/kb/question.php?qstId=112

 

[Coupe de jour]

Hib,


Very interesting info. In my case the right front motor was working intermittently when the ignition was cycled from off to on. Even after swapping motors, the intermittent condition still occurred on the right hand side while the original motor from the right worked fine on the left hand side.

I just ordered a controller and custom chip from Bilstein today. I'll let you know if that solved the problem.

Thanks,
Kurt

 

[Hib Halverson]

Hib,


Very interesting info. In my case the right front motor was working intermittently when the ignition was cycled from off to on. Even after swapping motors, the intermittent condition still occurred on the right hand side while the original motor from the right worked fine on the left hand side.

I just ordered a controller and custom chip from Bilstein today. I'll let you know if that solved the problem.

Thanks,
Kurt

Intermittants are almost always problems with wires or connections. Have you troubleshot the system per the service manual?

 

[Coupe de jour]

Yes, I did use the manual. When I discovered the intermittent function of the right front motor, I ruled out the motor by swapping it with the left front motor. Other than that anomoly the system checks out according to the book. I will let you know whether the new box fixed the problem. It should be here any day.

Thanks,
Kurt

 

[e3imcba]

Thank you immensely, Mr. Halverson, for the information on the FX-3 system. Fixing things has never been a problem for me, If I can figure out what to fix! I haven't given much thought to the suspension since unplugging the Bilstein computer some time ago, but upon reading your reply, things make more sense to me now. My connections and actuators all seem fine, and the shocks were rebuilt by Bilstein. I'll re-install the computer and see how things go over a period of time. -- John A.

 

[e3imcba]

Hi, Kurt! Did you get your Bilstein computer? What was the result? I'm kind of holding my breath because I seem to be having the same problem. The warning light was intermittent after the shocks were rebuilt, then became permanently on. Codes 13 & 14 came back after switching the left and right front actuators - same as before. I expect the result would be the same if I swapped out the rear ones, too. What Hib Halverson wrote about the shock rebuild makes sense, but it now appears I have a different problem. Have you found the magic cure? -- Thanks! -- John A.

 

[Coupe de jour]

John,

I have installed the new computer and I am very happy with the results. I am using the Slalom 1 chip with stock valved shocks and the car rides much better than it did on the stock chip. Also no more fault codes.

I spoke with a guy named Bill Hindorff at Bilstein. He is "the Corvette guy" in their Motorsports department and he knows a lot about FX3. As I said, the controllers are available with removable chips for $241.00 and can be ordered as follows:

Slalom 1 P/N AK2113
Slalom 2 P/N AK2114
Slalom 3 P/N AK2115

Bill also mentioned that a lot of intermittent fault codes can get thrown when you replace the shocks and don't replace the rubber bushing at the top of the shock. He said that the tolerance is pretty tight so if the bushing is worn it can cause the actuator to either bind or lose contact with the adjustment shaft on the shock. For about $12 for the front end, Bill can supply urethane bushing they had built by Energy Suspensions that will permanently solve that problem. He did not have that P/N handy but when I get it I will post it.

The last thing Bill mentioned was that you really don't want to use the Slalom 2 or Road Race controllers listed above unless you have had the shock revalved because the stock ones come too soft from the factory to notice a difference. Bill said they could also set up a chip with the stock setting if you are not going to race the car.

Bill can be reach @ (800)537-1085 (San Diego)

Kurt

 

[e3imcba]

Thank you, Kurt, for the info on the Bilstein computer. It sounds like just what I need. I'll post my results after I've replaced my computer and done any other related work.(not sure when that will be). -- John A.

 

[e3imcba]

Hi Kurt! I've talked to you before about my FX3 problems, which unfortunately are still there. Same old codes 13 & 14 even after swapping the front actuators, resetting the codes, and installing a new Bilstein computer! I must have a wiring problem. I've found factory shop manuals on line, but no wiring supplement so far. I'm determined to get that expensive suspension system working as it should. Do you have any suggestions for this frustrated Corvette nut? I'd be really grateful for any help I can get! Thanks! -- John A.