Speed Sensitive Suspension and the "SERVICE RIDE CONTROL" message

[French member]

Thank you NickySantoro.

[austinDeville]

(Sorry in advance for a long post)

I think I implemented the relay mod correctly, but I still get the "service ride control" message. "94 SDV", the earlier poster who reported the same, if you figured it out could you post what you did. Otherwise, if someone could give any advice, it would be appreciated. Here is what I have done:

Following the instructions, I tapped into the wiring for switched power and ground. I connected the gnd line to pin 30 of the relay and the power line to pin 85 of the relay and verified with a volt-ohm meter that the ground line was indeed a ground and that the voltage line contained switched voltage.

Following the instructions, I cut the red wire (C15) going to the module and connected the module side to pin 86 of the relay and the wiring side to pin 87A of the relay. I checked the behavior of these signals with the meter. The module side of the red wire, now attached to pin 86 of the relay, gets pulled to ground by the module about 6 seconds after i turn the key to the on position. My understanding is that this is the module sending the signal that becomes "service ride control". When this occurs the wiring side of the red wire, now attached to pin 87A of the relay, changes from ground to about +8.7 volts. I am assuming this is resulting from the relay getting energized and causing an open circuit between 87A and 30 (ground).

This behavior is basically what I expected from the description of the circuit mod. I thought that possibly 8.7 volts was not enough for the fault logic circuits (i didn't really believe this, but was clutching at straws) , so I tried, as a test, putting a 500 ohm pull-up resistor between the relay pin 87A (wiring side of red wire) and relay pin 85 (+12). With that test in place the voltage on wiring side of the red wire after the relay is energized is about 10.2volts instead of 8.7, but I still got the "service ride control message".

The following is the behavior of the fault codes with four conditions (1) wiring mod, (2) original wiring, (3) open circuit for C15, (4) Wiring harness side of C15 grounded.

Starting with the modification installed, the car stationary and all codes cleared, I switch on the key. After about 6 seconds the “Apply Brake to Shift” message comes up and then the "Service Ride Control" message comes on. Next I display the codes and there is only I039 Current. If I clear the code, then I039 does not come back.

Same test, but this time with the wiring restored to the "pre-modification" state and the behavior (messages and codes) is identical.

The next test was leaving the red wire (C15) cut between the module and the wiring harness. The behavior is almost identical. The only difference is the order of the messages – the “Service Ride Control” comes on before the “Apply Brake to Shift” rather than after.

And lastly, grounding the wiring harness side of C15 circuit. With this wiring there were no codes at startup, hoping that this was the solution I was looking for, I drove the car around, and after about 1 block the “Service Ride Control” message came on and checking the codes, this was indeed I039.

Not knowing precisely how the fault detection works, I do not know how to proceed. I am guessing that the mod is working as it is supposed to and something else is causing the I039 message. Is this crazy talk?

I have seen in this thread that there is a flashing light code that can be checked from the model. The exact text in the thread is “You get into the SSS/CCR system by grounding pin 'C' on the ALDL. On the module there is a white plastic window with a LED behind it. It will flash codes after pin 'C' is grounded. It will repeat the codes as long as it is grounded.” So my question is: what is an “ALDL”, where is it, is the “pin C” on the mysterious ALDL and is, the ALDL just the module back I the trunk which I have been hacking at or is it something else?

[NickySantoro]

The ALDL is the grey connector under the dash on the driver's side about 3" to the right of the parking brake. The pins are marked but the markings are hard to see.
You noted cutting a red wire going into the module. On mine I cut the pink wire coming out of the module. Do you have a RED wire coming out of the module? If you have RED going in and RED coming out, could you have cut the wrong wire?
For power I spliced into the solid brown wire. I ran pin 30 to a ground.
I know the instructions call for RED but seemingly that becomes PINK on the output side of the module on my Eldo. I know little of things electrical but I posted what worked for me. I forget where I got that red/pink transition info, but it was from someone on another board who had a handle on the issue.

[caddybear]

Hi guys,

I think I have a fix for ‘SERVICE RIDE CONTROL / 84’ error message for at least ‘93-’97 STS / ETC with Northstar engine. (I did it on my ’93 STS, but it should be the same or similar for the other years).

There are two main causes for this message – active strut failure and accelerometer failure.

As it’s stated in the shop manual, the resistance of the electric part of the strut should be between 1.5 and 3 Ohm. As it turned out, a resistor within the specified range may successfully simulate this electric load.

I didn’t go into a deep evaluation of this thing but potentially, the current through this load may be high and produce quite an amount of heat (although I didn’t see it getting hot during few weeks of operation). So, as a precaution I would recommend to use resistors for dissipation of 5 or 10 watt. I’ve used two 2W resistors (5.1 Ohm) connected in parallel (for each ‘simulated’ strut). Obviously, the wires going to the strut must be disconnected.

All the resistors have to be connected on one end to CKT 1112 (power). The most convenient (but not that easy to identify) place is the harness in the front of the trunk which makes a loop right in the middle going from the bottom of the rear back seat to the trunk floor.

The wire you’ll be looking for is a thick white one. For its positive identification I strongly recommend to ring it through to the relay. It’s relay ‘F’ in the relay block under the hood (you’ll have to remove the protective cover around the fuse block – under the hood) and it’s the rear one, in the row closest to the fender. Remove the relay and ring through the wire to the trunk.

Once you have the feed from CKT 1112 (in the trunk) you have to identify the wires for the appropriate strut(s) on the 8-pin connector (C3) of RSS module. For RF – D; LF – E; RR - C; LR – E (see the drawing). Cut the wires for the struts to be ‘unsupervised’ and connect each one through its own resistor to the feed (CKT 1112).

Isolate the wires and attach the resistors in a suitable place – remember, they MAY produce a lot of heat…

The second cause may be the accelerometer’s fault. Fortunately, they also can be simulated by the resistors. As it’s said in the description of error codes S070-S073, which are relevant to the problem, the codes and the error message are set if the voltage from an accelerometer is out of 0.5 – 4.5Vrange for more than 0.5 sec. As I’ve figured out, this should be the voltage between ‘+’ and ‘-‘ signal wires of the accelerometer (not the voltage from ‘-‘ or ‘+’to the ground).

As a result, I’ve got a three-resistor divider, which has 100 Ohm resistor from the ground to the ‘-‘ signal wire (as it is in the real accelerometer), 63 Ohm resistor from ‘-‘ signal wire to ‘+’ signal wire and 470 Ohm resistor from ‘+’ signal wire to +8Vsource for the corresponding strut (see the drawing). I believe 5-10% deviation from these values should be ok. (The actual accelerometers, obviously, should be disconnected).

Here the current is minimal so you can use 'regular throughhole’ resistors 0.25 or 0.125W and it may be a very good idea to install them on a piece of a blind board.

The parts you can order at digikey website (with delivery to your place for a reasonable price).

So, if have any comments or would be so exited that you’d want to send me a couple of bucks for beer for going through the hassle of posting this info just contact me at caddybear at live dot com.

Good luck!

[warriorjoe]

austiinDeville:

I have a 1994 sedan deville. Intalled the relay to eliminate the SRC message - got same result you did. However, I did get it to work last night, temporarily. Made several runs around block, and SRC message never came up. However this morning when wife drove to church, the SRC msg reappeared along with I039 code (quits when you push the INFORMATION button until restart the car). So I don't know what's going on here.

Today I lifted and grounded the IPC lead at module and msg went away. It came back on when I exceeded 15MPH. Found in manual that the I039 code is generated if the C15 signal is LO greater than 15 mph, and if C15 is HI less than 5 mph. Hooked system back up original (my problem was intermittent and it works OK sometimes for a while). Then noted that C15 was LO (0 volts). Got in trunk with flashlight, had wife drive around block, and observed that C15 went HI at 10mph and over, and dropped back LO when speed went below 10mph. So in this case, I can't see how the relay mod could ever work for me, since with the relay the IPC lead is HI after turning the switch on.

I am a retired electrical engineer, and have extensive background in electronics, so I am considering building a logic circuit that picks up the speed info to the module, and use that circuit to operate a relay that will cause the IPC lead to go from GRND to HI at >= 10mph, and drop back out to GND at <=10mph.

However, I wonder how you solved this problem, if you were able to. The codes in my case indicated a bad LF strut. The struts wiring is still connected. I wonder if that has anything to do with it, since most of the mods posted seem to be related to changing to passive struts in which case the strut wiring is disconnected???

So how did you fix your problem like this?

Thanks!