1993 ETC, S021 Current

[Cadillac Jim]

I got an email from a fellow with a 1993 ETC. An excerpt from his message:

My Cadillac is a 1993 El Dorado Touring Coupe [this is the 295 hp Northstar]. Recently an error message appeared on the dash panel "Service Ride Control System" [this means it has RSS]. A mechanic looked at the four struts and determined that the right rear was leaking. I replaced both of the rear [shocks] with Arnott [shocks]. We could hear the compressor work and the shocks did adjust properly. However, ever since replacing the rear struts, the error message "Service Ride Control System" comes on frequently on an intermittent basis. We then replaced one of the sensor wire assemblies with one from a junk yard and the same error message stayed on constantly. We then put the original sensor wire assembly back on and the message still appears, but much less frequently -- leading me to believe that this is where the problem is.

...error codes ... are: S0021 (this one reappears after being reset or cleared). The other error codes which are in "history", but not current, are S0044, S0055, S0061, and S0063.

CURRENT

S021 Left Rear Damper Solenoid Valve Short to Ground/Open
This is where the problem is. It's a short or break in the wiring harness.

HISTORY
S044 Lift or Dive Signal Fault
S055 Resistor Module Short to Ground/Open
S061 Right Front Position Sensor Fault
S063 Right Rear Position Sensor Fault

S055 is a mystery to me; the others are probably ride height sensor codes. Since they are intermittent, they are probably loose connectors or worn insulation.

You should have come to Caddyinfo before you had the car worked on. The likelihood that the rear shocks were leaking is just about nil. It’s very common for mechanics with brake fluid in an oil can (for lubricating rubber bushings and grommets in the shop, a legitimate use) to squirt some on the shocks and show it to you; it’s happened to me a number of times over the years – and I always say no, look a week later, and the shock is dry. From the CURRENT code, there is a problem in the wiring harness, something you have already figured out. A leaking shock will not throw that code. And, changing the shocks won’t fix that code. Without knowing the part number of the Arnott shocks or looking on their web site, I can't tell whether you downgraded your car by disabling RSS on the rear or not, but so far as I know, Arnott does not make RSS shocks; the only manufacturer that I know of that does is Monroe.

At this point, I would suggest that you look over the old wiring harness (apparently the best one) foot by foot and look for damaged insulation, a hinge point that may mean a broken conductor inside a wire, and loose terminals inside connectors.

And, get another mechanic, one that is ASE certified. Look for the ASE logo on a certificate on the wall:

Check the name and date, and ask who is the guy named, and will be be doing the work on your car (or at least supervising it).

[Göran W]

Did anyone check codes BEFORE replaceing shock???

[Cadillac Jim]

I haven't heard back from the owner yet, but his original e-mail said that he got a "SERVICE RIDE CONTROL" message on the dash, and that a mechanic "looked at the four struts and determined that the right rear was leaking." So, apparently not.

[93CadillacOwner]

Unfortunately, I did not have the codes checked before replacing the rear shocks. Lesson learned (a rather expensive one). I will probably reinstall the old ones and troubleshoot the wiring.

[Cadillac Jim]

A message on the DIC happens because a module has found a problem that has it throw a code. Any decent mechanic will read the codes to find the message, then use the message to diagnose the problem.

Look for the ASE certification on the wall. A quick way of finding out if it's current is to note the name and date on the certificate. If the date is more than 5 years old, and you can't find a more recent ASE certificate, wander off. If the certificate is in date, wander over to the shop door and ask "Is <certificate holder> around?" If nobody knows, wander off. If he comes over, ask him if he has an OBD I code reader (for your car!). If he doesn't instantly look you in the eye and say "yes" then wander off.

Re-installing the old shocks may not be the best thing to do if they are older than 50,000 miles or so, and on a 1993 they may be a lot older than that. Look at them yourself before deciding.

What I find interesting is that when we replaced the right rear wiring, that had an effect on the frequency and duration of the error code appearing. Yet the S0021 error code pertains to the left rear damper solenoid valve. By the way, is the damper solenoid valve part of the sensor wiring piece (aout 12 inches of wire and springs, etc.) or is it located elsewhere?

The wiring you used to replace the right rear wiring was bad. The damper solenoid valve is part of the rear shock but the code doesn't necessarily mean that the solenoid itself has a problem because the wiring can case that same problem. Nearly always, it's the wiring and not the solenoid, and most of the time it's the connector terminals, and when the connector is clean and tight but you get that code it's a pinched, shorted, or broken wire that you can find by looking.

[93CadillacOwner]

I have subscribed to this topic now. Thanks again Cadillac Jim for all of your help and insight. At this point I will probably just keep the Arnott shocks installed and try to find the code problem apparently caused in the left rear wiring connectors.

[Cadillac Jim]

Keep us posted on how you are doing.

If you prefer to DIY, you need a concrete floor that is comfortable to work on, a mechanic's trouble light, a creeper, and a way to keep the car safely off the ground. Some people prefer a floor jack and jack stands, and if you need to take off the wheels that is necessary. For most work under the car back when I did a lot of that, I preferred drive-on ramps, but you need to have a bit of skill beyond the ordinary to drive the car up on those safely.