Check engine light just came on

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Ok that?s good one lee thing. Did you know you could use a 2-3 foot long piece of heater hose as a stethoscope to listen for vacuum leaks? I don?t think the brake fluid level would cause a ?check engine? light, as there should be a light dedicated to low fluid. Wouldn?t hurt to check it as they worked on you breaks reasently. As long as the brakes work and the engine aren?t throwing any codes I would just drive it. Just a random thought look under the dash and see if there are any wires that the brake pedal might pinch or push agenst when it is depressed. The check engine light is mostly emissions based, as you know so doing long distance troubleshooting is tough. The thing that is interesting is the part where the light goes on when you press the brake pedal part way. Does it go out when it is fully depressed? Was the coach running ok before this latest problem?
Bill
 
I don't know if it goes out if I push it further. I know it is weird that it is acting this way and very illogical. I have checked out the brake wires as best I can, it is hard to see under the dash. The coach has been and is running great. Today I disconnected the hot lead to the engine battery for 10 minutes and then reconnected it. I am taking it in for an oil change on Wednesday. I will have the brake fluid checked then. I looked the top of the engine over and the only thing I found wrong was a NoX sensor was broken off. I tried to buy a new one but I needed to know if it was a 16 bolt or a 17 bolt transmission pan. I will have that checked out during the oil change and then get the proper sensor. It should be easy to change. Thanks for the suggestions Bill.
 
I just read through this thread......

Two things stand out.... Trans fluid "Light brown" and brake pedal issues......

I would highly recommend that you service your transmission soon. Your transmission holds about between 10 and 15 qts of fluid. Pulling the pan and changing the filter will only replace about 1/3 of the total fluid in the trans. Most of the fluid is contained in the torque converter. It is important to get that fluid out as well.

Your trans fluid should be red...... any hint of brown is a sign that the trans fluid is breaking down. This will cause extreme wear on the transmission if left that way. The trans fluid is the "Blood" of your transmission.

If you haven't flushed your brake fluid in a long time, this may be the time to do that as well. Brake fluid burns just like trans fluid does. It's important to replace all of the brake fluid every few years on heavy vehicles. When the fluid gets hot, it can take on moisture. If you have moisture in your brake lines, it can cause corrosion and result in some very expensive brake repairs. Also check to be sure that your brakes are not worn-out.
 
Worrying about the trans fluid and brake fluid at this point is not necessary. I tried driving it today and it is really acting up. At one point the engine quit and it was hard to start. I managed to get it back to the shop. It still isn't showing any codes. However the computer thinks the brake lights are on when they are off and visa versa. He checked the ground and it appears ok. Right now he is checking on the cost of a new computer. He thinks it is either a computer problem or a wiring problem.
 
SeilerBird said:
Worrying about the trans fluid and brake fluid at this point is not necessary. I tried driving it today and it is really acting up. At one point the engine quit and it was hard to start. I managed to get it back to the shop. It still isn't showing any codes. However the computer thinks the brake lights are on when they are off and visa versa. He checked the ground and it appears ok. Right now he is checking on the cost of a new computer. He thinks it is either a computer problem or a wiring problem.
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I hate it when these techs start "Part replacing" without actually knowing what the issue is. That computer is EXPENSIVE and is the least likely item to go wrong. I hate to say this, but I would go to a Chevy dealership. Those guys are trained to work on that specific issue. They have the test equipment to check each sensor. If they replace the ECM and it doesn't fix the problem, they won't charge you for it. If an independent replaces the ECM..... he has no way to return it (after installing it) and you may be stuck paying for something that didn't fix the problem.

The other thing is, if you get 500 miles down the road and it acts up again (with the same issue)....... any Chevy dealership will honor the 90-day warranty.

Good luck...... I hope it all turns out OK for you.
 
SeilerBird said:
The mechanic is not "part replacing". He asked me what I wanted to do and I am having him check on the price of a new computer.
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If the mechanic has no codes or other indicators, he is "part replacing".  Sometimes that's what it takes.  However, a $300 +/- computer is a pricey guess.  Personally, I'd risk $50 or so and have him change the oxygen sensor before I sprang for a computer.  Oxygen sensors wear out normally, computers do not and the sensors do not always throw a code when bad.  At least you would have a new fresh sensor you shouldn't have to worry about any time soon.
 
The mechanic has been in contact with someone who works for AC Delco and the guy helped him troubleshoot. He just found a bad switch on the brake pedal and he has one ordered. It will be here tomorrow so I am spending the night at the shop. The problem with going to a GM dealer is the fact I have three cats in here and I live in here. I can't just drop it off and pick it up a few days later. I have to stay with the vehicle. This guy allows me to do that. No GM dealer would ever allow that.
 
Tom,

If it comes down to an ECM, Have him check salvage yards for one. I know that we have a local yard that sells them with a 90 day warranty for around $100.00

Steve
 
SeilerBird said:
The mechanic has been in contact with someone who works for AC Delco and the guy helped him troubleshoot. He just found a bad switch on the brake pedal and he has one ordered. It will be here tomorrow so I am spending the night at the shop. The problem with going to a GM dealer is the fact I have three cats in here and I live in here. I can't just drop it off and pick it up a few days later. I have to stay with the vehicle. This guy allows me to do that. No GM dealer would ever allow that.
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Starting with replacing a bad switch sounds a lot more sensible than starting with the ECM...... As Molaker stated, you can replace a lot of sensors for the price of an ECM and those sensors do go bad.

ECMs are very tricky. I would not recommend a used one unless it had the exact same (13 digit) part # on it.... very unlikely that you would find one exactly the same. If you hook up the wrong one, you could start a world of problems. Besides the fact that you have no idea where that ECM came from..... it could be a parted out flood vehicle.

My guess is that you may have 2 (coincidental) issues going on at once. That's a lot more common than you may think. The stop light/crz control switch may be causing the indicator issue but I doubt that it is causing the engine to quit running and hard start issue.
 
Molaker said:
If the mechanic has no codes or other indicators, he is "part replacing".  Sometimes that's what it takes. 
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You missed my point. The mechanic is not part replacing, I am the one doing it by telling him to do it. But right now the computer is not suspect, the brake switch is.
 
Wavery said:
My guess is that you may have 2 (coincidental) issues going on at once. That's a lot more common than you may think. The stop light/crz control switch may be causing the indicator issue but I doubt that it is causing the engine to quit running and hard start issue.
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The engine only quit and hard started once. It is a very confusing issue to be sure.
 
OK Tom, Sorry to hear of your problem.  The Check engine light is emission related only so I would guess that you are maybe getting a bad reading from a sensor. If there are no codes stored then it is what they calll a soft code which means it comes and goes. There should be no relationship between the brake and the check engine light. The speedometer going hay wire might mean a bad speed sensor or possible a dirty connector at the speed sensor which is located on the output shaft of the transmission.

 
SeilerBird said:
The only time the speedometer goes haywire is the exact time the light comes on.
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That sure sounds like the speed sensor to me... That could explain a lot of symptoms........ I'm not sure on that vehicle but on most GM vehicles the speed sensor reports to the ECM and influences shift patterns, timing and other functions.
 
I am not sure on that year as to whether the speed sensor sends a signal to the computer or not. 1994 was a transition year so without the service manual I can't tell you. The truck chassis were kind of odd from 1992 to 1995 with different chassis going to OBDII at different times. Like I said, an intermittent light means the problem is coming and going. I don't think it is an eminent break down problem so I would drive it as long as it performs ok until the Ck Eng light comes on and stays on where you can get a hard code. 
 
My plan was to drive it till it breaks but after driving it today for about 20 miles it was clear I have to get the problem fixed. This is a 1994 coach on a 1993 chassis. It is OBD1.
 
Actually your plan is working, it's getting closer to the breaking point where it can be diagnosed. Sometimes the only way to solve these problems is to "swap" out parts, especially it there are two issues going on at the same time. Now you know why I have all these extra parts in my garage. I still don't understand why it hasn't sent a code ???

Too bad you missed Jane's buffalo burger.. :'(.we'll save you one.
 
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