Suspension, Brakes and Tires Discussion, ABS & Traction Control Warning Light in Item Specific Cadillac Discussion; I have a '99 SLS that has been a dream since I purchased it in 11/2006. For the last week ...
I have a '99 SLS that has been a dream since I purchased it in 11/2006. For the last week to ten days, I have had an intermittent ABS and Traction Control warning light on and an intermittent Service Suspension message in the DIC. I have checked the codes and they are as follows:
P1602 Current Knock Sensor Module Performance
P1644 History Traction Control Delivered Torque Output Circuit
C1736 History Compressor Relay Short to GND/Open
C1780 History Loss of Steering Position Sensor
C1783 Current ICCS2 DL Left Output Short to GND
C1785 Current ICCS2 DL Right Output Short to GND
U1040 History Loss of Class 2 Communication with ABS
U1255 Current Class 2 Communication Malfunction
(Serial Data Line Malfunction)
These warning lights and messages are intermittent in that they seem to come and go with little or no rhyme or reason. When the warning light condition exists, I lose the variable speed steering. I still have power steering but it is very stiff during this condition. I have also noticed that when the condition exists, the AC/Heat system is acting strangely in that it will not operate as set. I leave the system on Auto at all times and when the warning light condition exists, it will either not work or will blow only warm air through the floor vents.
The condition is random in that when I start the vehicle it will give me the warning lights and the adverse operation as listed above, but at random times while driving, usually when cornering, the warning lights will clear, my steering will return, and my AC/Heat functions correctly. This may last for a few minutes and the warning light condition returns with the subsequent adverse conditions.
Before I take this into a shop, sorry I lost the only mechanic I can trust, I wanted to present this scenario and see if you had any suggestions. Is this truly a suspension problem or is this an electrical problem? The only work I have had done on this vehicle is routine LOF which was completed less than 200 miles ago along with an engine flush. Is it possible the tech doing the service jarred a connection loose?
....For the last week to ten days, I have had an intermittent ABS and Traction Control warning light on and an intermittent Service Suspension message in the DIC....
The condition is random in that when I start the vehicle it will give me the warning lights and the adverse operation as listed above, but at random times while driving, usually when cornering, the warning lights will clear....
Is this truly a suspension problem or is this an electrical problem? The only work I have had done on this vehicle is routine LOF which was completed less than 200 miles ago along with an engine flush. Is it possible the tech doing the service jarred a connection loose?
Did you ever find the solution to this? My 1999 STS is doing the EXACT SAME THING. I love the car, other than this nagging problem. My dealer thinks both the EBTCM and BPMV are bad. I swapped the EBTCM with a used one and still have the same issues. Any help is appreciated.
Posts 3 through 6 hit the target on the largest single problem with automotive forums that attempt to provide diagnostic and repair information assistance. And that would be the selfish lack of courtesy of a follow-up post from the original poster to say "xyz fixed the problem".
The problem is repaired and the original poster goes away until yet another problem appears. How that attitude makes a contribution to the remainder of the readers is beyond my ability to comprehend.
And I am not pointing a finger at the original poster of this thread. Far from it. It's possible the cause of this problem has not been positively indentified.
I had posted quite a while ago, that I had the exact same problem with my 99 STS. I belive my dad has since identified the problem.
He believes it's the ignition switch. It powers several relays, one of which (relay #3 I think) is in the fuse block underneath the rear seat. It powers just about everything listed in the original post. He used a meter and checked for the 12 volts that should be there when the ignition is set to 'on'. Upon cycling the ignition switch, sometimes the power would be there and sometimes it wouldn't.
My dad set up quite the slick override. I'm not sure of the exact details, but he ran a wire from the rear fuse block to a regular household light switch that he placed under the driver's seat. At the fuse block, one end was hooked up into the positive slot that always had power, and the other end was hooked up to a slot which would normally power the relay. So he directly overrode that relay.
Now all I have to do is turn the switch (which I have named the 'ghetto switch') on when I start-up but most importantly.... REMEMBER to turn the switch OFF when I shut down. As the battery timeout doesn't work with this override of course. My Dad's an electronic technologist so I guess it was fairly simple for him to do. I hadn't a clue. He looked at the manual and saw the pain of changing the ignition switch and did the above fix as a temporary measure. The climate control, Magnasteer, and many other systems work perfectly when the switch is on. My ABS and TC lights are still lit, but I think that's because the DTCs say I need a wheel bearing and a height sensor.
Now I just have to buy an ignition switch and get my Dad to change it. Any ideas on where to find one?
In short, I needed a new ignition switch. The great thing is these are available from most auto parts stores for $26-$60, or from a dealer for $125. I had a local repair shop replace my ignition switch with a new GM part and have not had this problem since. For those who do their own work, A fellow forum member posted the repair procedure in the link above. I can also email the the GM service procedure to you (website will not let me post a .mht file). If I figure out how to save this .mht file as a .pdf, I will post it.
Hello everyone. I've had a lot of problems since I first bought my car. Most of them have either been diagnosed or repaired by now. However, there still are a few codes that keep coming back. I'll only ask about a couple here so I don't bombard eveyone.
First a short history. When I purchased the car, the ABS and TC lights were always on. Using the FSM and the DTCs that said "ABS C1233 - Right Front Wheel Speed Circuit Open or Shorted" and "RSS C1761 - Right Front Position Sensor Input Fault", I replaced the front right position sensor and the front right wheel bearing. After doing this and clearing the codes, I started up and the ABS and TC lights did not light up. It was a proud moment, I had never seen that happen before since they would always light and I would have "Service Suspension System" and "Service Stability System" on start up. I just did this repair yesterday.
I went for a drive. Everything was fine for the first few miles. I enjoyed having first gear now that traction worked (much better performance ). But then I heard a chime and the ABS and TC lights lit up along with "Service Stability System". I immediately pulled the codes and now it showed:
C1736 current - Compressor Relay Short to GND/Open Circuit (something I had before but wasn't always current, sometimes history)
C1225 current - Left Front Excessive Wheel Speed Variation (never seen before)
As soon as I clear all codes, the ABS and TC lights extinguish and everything is fine for a while. And here's another weird thing. Sometimes the ABS and TC lights illuminate without the "Service Stability System" and only the C1225 is current. Other times the "Service Stability System" is displayed at the same time the ABS and TC lights illuminate and code C1736 is current as well. Could this be a coincidence? I wouldn't think so because if the "Service Stability System" displays, it'll do so at the same time as the ABS and TC lights illuminate.
Here's what I'm thinking when it comes to the C1225. My front left speed sensor is on its way out Since the front right bearing was always bad, the ABS probably saw that immediately and shut down the ABS and TC systems and stopped monitoring any further. Now that the front right bearing has been replaced, it attempts to keep the system active. If I have a flaking speed sensor in the front left hub, it'll trigger the code once in a while. I'm thinking it wouldn't have had a chance to monitor the front left because it immediately sensed the bad right one and shut down. Does that make sense? I'm going to clean the connector tomorrow, but I'll probably have to replace it though.
As for the C1736 I have no clue. Would this code trigger the "Service Stability System"? It's talking about the air compressor for the electronic level control for the rear shocks, right? It seems to be unrelated. I'm lost.
I should also note that I'm overriding the IGN 3 relay that is in the fuse block under the rear seat. I believe my ignition switch is bad (see above posts) My Dad installed a temporary switch that powers the relay. I just turn it on before I start the car and vice versa. I don't think it should affect the troubled areas but I thought I should note it just in case.
If you've read to here I am very grateful for your time and appreciate any insight anyone has to give. I tried to keep it short but that didn't happen. But I think if you don't give all the details, why should someone else help me troubleshoot when I don't take the time to fully explain the problem, right? My car is approaching a trouble free status and I couldn't have done it without the helpful people here on the forums, and of course my mechanic.... Dad
UPDATE! I pulled the wheel off and the wire that leads to the speed sensor connector was kinked. My Dad cut that piece out and used a couple of crimps to reconnect the wires. He also used a couple tie wraps along the length of the wire to help ensure it wouldn't kink again around the crimps. That coupled with some electrical tape to seal the repair and... the C1225 code hasn't come back yet!
I've only driven it about 60 miles or so, but before that code would have set several times within 60 miles. I'm hoping the ABS problem is solved.
However, I still get the C1736 code about the compressor. Any ideas on that would be great.
My apologies for the lengthy post above, especially since a big portion of that problem has hopefully been solved.
C1736 refers to part of the ELC - rear level control and compressor. Do you hear the compressor run for 3 seconds, about 6 seconds after key, start? If so, pop the trunk with the engine running. You and an assistant sit on the trunk lip. Does the compressor run and level the rear ? If so, hop off and listen in the RR wheelwell for escaping air. The rear should drop to level.
No good?? Check your owner's manual for the location of the compressor relay - either the engine room fuse box or if there is fuse box under the rear seat - the relay is protected by a fuse, and from there you'll have to trace the wiring, because the DTC refers to a relay ground, not a compressor malfunction.
Ok thanks for the advice. I believe the I can hear the compressor run for about 3 seconds 6 seconds after key start. But I'm not sure if it comes on again to level itself after weight is increased. I'll check this tomorrow and report back.
Also, I know when I jack the car up, I can hear air escaping from the rear. I'm assuming that is normal?
Alright, I've found out that sometimes the compressor will turn on for a few seconds after engine start, and sometimes it won't. I'm guessing when it doesn't, the code C1736 will be current and when it works the code will be history, lol.
So following Submariner409's advice, it sounds like the next step would be to check the relay and then the wiring to check for continuity?
Now I also sometimes get RSS codes C1783 and C1785. Usually listed as history. Could they be related?