: TCS C1233 and ignition problem? 97 SLS

03-07-05, 06:40 PM
I bought my 97 SLS about two months ago and it has been nothing but headaches. I had major issues with a sensing issue, which after much hardship was solved with a PCM replacement.

The car is still not running right. Seems to be misfiring. Dealer says plugs and wires is the source of the problem, however, after three misdiagnoses (thermostat, temp sensor, and wiring) before fixing that issue with the PCM, I have little faith in their opinion. I heard that sometimes the EGR valve can cause this 'misfire' problem or possibly the electronic ignition???

To further complicate matters, yesterday my ABS and TRACTION CONTROL lights illuminated. When I went into the fault code function on the environmental panel, it gave me a fault code of TCS C1233...

If anyone is knowledgeable about either of these issues, please post or e-mail me direct... or both. I am so distraught with this vehicle, I just want to get rid of it at this point, but I want to minimize my losses by selling the vehicle in perfect running condition. It is actually a very nice car. Only has 69,000 miles, but I have learned through all of these issues just how many things can go wrong with this car and simply do not have the finances to afford the risk.


03-07-05, 07:32 PM
The C1233 means Right Front Wheel Speed Circuit Open or Shorted. There is a sensor in the wheel bearing/hub to detect wheel speed. The wires for it may be disconnected or pinched, or the sensor may be bad. Check the wiring first. If it's the sensor, the whole bearing assembly needs to be replaced. www.rockauto.com has the axle bearing and hub assembly for $107 and probably any mechanic can swap out the parts relatively quickly.

As for the rest of the issues, why don't you post exactly what problems you've had and what was done about it. Also include what's currently wrong and any other codes in the system. There are a lot of knowledgeable and helpful people here who can tell you how to get it fixed and save you *lots* of money, heartache, trouble, and time. The dealership is probably not the best place to go if you want to cut down your maintenance and repair costs.

For starters, what was the "sensing problem" you described earlier which required a PCM replacement to resolve? I would be willing to bet on the plugs and/or wires causing the misfire above anything else. If the EGR was causing a problem, it would set a code. If there are no EGR codes, I would say that's highly unlikely to be the problem. You can get ACDelco 41-950 plugs and 748J wires from www.rockauto.com for about $178 delivered (recommended) or you can go with lower cost parts if you really do just want to dump the thing. If the car recently had the fuel rail recall performed, there have been multiple posters here who had misfires and general engine problems after that recall was done, and as far as I know replacing plugs and wires fixed all of them. When the remove the wires for the recall, they might be intentionally damaging something or perhaps just disturbing the normally untouched wires tends to break the internals. Who knows, but I think it's safe to say that plugs and wires are your best bet for the misfire problem. Buy the parts yourself and do it yourself or take it to another trusted mechanic. The dealership will probably want to charge you $800 for that job.

We'll do our best to help get you through the hurdles and hopefully restore your confidence in the SLS. You might pay a little more for maintenance, but the car will probably treat you right and last a long time. And no, I don't have any interest in Rock Auto. I've just searched high and low for parts and they seem to have the best prices.

Let us know...

03-07-05, 11:14 PM
Michael, first off, I want to say thank-you for taking the time to reply. It is nice to know that there are people out there who are knowledgeable and willing to help without having something to gain. As far as the dealer goes, the original problem came up just before the car actually changed ownership. I was concerned, but not enough to back out of the deal. The gentleman I bought the vehicle from said he didn't want to lose the sale and he would have the problem resolved. He ended up taking the car in twice before I picked it up. The car was indicating and "engine overheat" condition, but it appeared to be a false indication. The first time, the dealer told him it was the thermostat, charged him $250. When he picked it up, same problem on the way home. He took it back, they told him temp sensor... another $250. So, this guy shelled out $500 bucks as he parted with this vehicle. I have the invoices. Anyway, everything is good to go. I complete the transaction. He signs the title over to me. I am driving the vehicle home that day... same problem. I go to the dealer and speak to the advisor on the invoices. The dealer was very patient with me and spent a lot of time looking at the car and going over some of the wiring without charge. I tried like hell to get out of paying a dime since I don't really have it. They cut me some slack on the PCM. They quoted $425. I payed $260. I priced the part online at around $200. I would have attempted it myself, but I guess it has to be 'flashed' and I don't believe I have access to the equipment to accomplish that?

Since, I picked the vehicle up from the dealer, the overheat indication problem has ceased, but the car is not running right. I cannot be sure if the car was doing this before aforementioned work or not, because I believe the system retards timing to reduce engine heat when it senses an overheat condition. So, I don't know if it was running bad (misfiring) before the work, or if this condition is a result of something they did, or both?

As for the TCS code. This evening, I drove the car and the ABS and TRACTION CONTROL lights have extinguished. I did not take the time to view the codes, but, I don't know what to anticipate with that issue?

As far as the plugs and wires... As a point of interest, the dealer wanted $250 for parts and labor. I thought they were out of their mind. I am surprised how expensive the parts actually are. I was going to change them myself last weekend, but to my dismay, I could not find plugs 1-3-5-7. I was told they are on the back side of the engine and best accessed by getting under the car. Unfortunately for me, I live in an apartment and do not have a great deal of tools, but from what you are telling me, it sounds like the plugs and wires are the best place to start. 2-4-6-8 are a piece of cake to get to. Are the other four plugs anywhere near as easy to access from underneath? I'll check out Rock Auto.

If you were me, what action if any would you take at this point regarding that TCS issue with regard to the fact that, at the moment, the lights have extinguished?

Thanks again for your time and effort. It really is greatly appreciated.


03-08-05, 10:51 AM
So would you say that the rough running and misfire started immediately after the PCM was replaced, or did it start at some point after that was done? It's possible something wasn't correctly flashed or calibrated in the PCM that the dealership will have to fix (I would assume at no charge since they did it wrong in the first place). Not being a PCM expert, though, I can't really speculate about what it might be. I think before you buy plugs and wires I would like to hear from one of the experts here about that possibility. If the misfiring started right after the PCM was replaced, I would want their opinion first. If not, I would start with the plugs and wires.

The rear bank of plugs can be accessed from above. It's a little tight, but I've changed plugs in my '96 SLS (same motor) twice without even removing the coils. (I made the mistake of using Bosch plugs the first time and they are absolutely JUNK) You need a plug socket (can't remember which size), an extension (maybe 12" or 18"?), and ratchet. Preferably you should have a torque wrench for reinstalling them, but if not, just don't overtighten the plugs. Anyway, you can get to them from the top. Take a look behind the intake with a flashlight and you'll see where the wires are for the rear bank. As for doing it outside versus in a garage, go for the garage. :-) If the dealership wants $250 for the job, make sure they'll use the AC-Delco plugs 41-950 plugs and 748J wire set, and that's a good price if they do.

As far as your Traction Control light issue, if you can get the right front wheel off, look for the wires that go into the wheel bearing and make sure they're connected to the harness that goes behind the wheel well. If the wires all look intact and everything's plugged in and OK, it's probably the sensor. That will require a bearing and hub assembly replacement. The part is about $110 for that and it doesn't take long to do if you have the right tools. I don't know what a dealership would want, but probably a lot more than that. If you buy the bearing for $110, take it to any trusted mechanic and they should be able to do the R & R.

03-08-05, 11:24 AM
The back plugs are accessed by taking the coil packs off. That's pretty easy.

03-08-05, 11:38 AM
I've done it both times without touching the coil packs. It would make it a little easier, but it's not required on my car at least...

03-08-05, 08:21 PM
Mcowden, I agree you can do it, and sprj can do it that way someday. He sounds inexperienced so removing the coil pack makes it easier for him. I sometimes get lazy about typing good long explanations like you did.

As a little aside...One of the car radio shows was talking about changing plugs on cars and said how easy some of them are from the bottom, but extremely hard from the top. The N* is actually fairly easy.

03-08-05, 08:55 PM
Just to confirm what Mcowden & Zonie said, I just did plugs and wires on my car and my wifes "96 Bonneville (3800). The Northstar was a piece of cake. I didn't have to remove anything to get at the plugs. You have to use the brail method to find the hole to get the plug back in but it was quite easy. The 3800 was another story and I drew enough blood to prove it.

03-12-05, 09:47 PM
Another ? The car runs smooth when it is cold (first 5 - 10 min ). Does that still sound like a potential plug/wire problem or is that indicative of another problem??? I am trying to avoid spending any unnecessary funds/time by diagnosing as accurately as possible before taking action.

08-19-05, 04:33 PM
There is a recall on the left wheel speed sensor that I think is causing my problems, which are charging system problems (removing battery and alternator from car and testing showed no problems). Anyone with any experience on this?

08-19-05, 07:23 PM
There is a recall on the left wheel speed sensor that I think is causing my problems, which are charging system problems (removing battery and alternator from car and testing showed no problems). Anyone with any experience on this?

If the wheel speed sensor is the problem, it is remedied by replacing the wheel bearing/hub on the affected wheel. The sensor is integrated into the bearing/hub assembly, so you have to replace the whole thing. The job is not difficult at all if you have basic tools, but you may need a bearing puller (some come out easy, others require a little persuasion) and you will need a large socket for the axle nut. You can get the bearing/hub from www.rockauto.com or www.gmpartsdirect.com for a good price, otherwise, the major chains should have it or be able to order it. The AC-Delco bearing/hub for front wheels is about $175, and there are cheaper brands so you might get it for around $120. Rock Auto wants $255 for the rear one.

I'm curious how there could be a recall on the left side bearing. They are the same on both sides. Are you getting a code for a bad wheel speed sensor? If not, that might not be the problem. I'm not sure if they can be tested or not. Scan tools might be able to give you live readings.