Check engine light just came on

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As soon as he removed the defective brake switch it did send a code. One thing is for certain, the problem I am having is when I push on the brake pedal and there is a switch attached to the brake pedal that is defective. So I am very hopeful this evening. The switch will arrive in the morning. I am also hopeful since the guy my mechanic is talking to seems to know his stuff. That is one of the signs of a good mechanic when he is not ashamed to admit he is stumped and seek help from higher knowledge.

If you ever go to Yellowstone and mention buffalo burgers the rangers will yell at you. It would be bison burgers. Just don't ask me my opinion of the intelligence level of any ranger who would say this.
 
Go back earlier in this post and look at one of the links I posted for you. It has a list of all the codes that could be causing your problem. The check engine light is for more than emission codes, no mater what some think. Go back and find that link and look at all the obd1 codes. Some will be hard and some will be soft meaning the light will only come on during a malfuntion. The trans does send info to the pcm. There is a brake code on the list. Even these old obd1 coachs are hard to trouble shoot without the proper manuals and a scanner, tech1 or eqiv. I bought my manuals and Mac code reader off of ebay, because I couldn't find anybody that knew what was wrong with my coach. You need to have a scan tool to read live data to trouble shoot some of these problems. If your trans fluid is NOT pink or red on the stick you need your trans serviced real soon. If your pcm will flash a code 12, key on engine off, it should be OK. If he changes the pcm, make sure he keeps and installs the memcal out of yours.
I know you stated you have a th400 trans, are you sure? Does it have OD? If so, it is a 4l80E, and it shows at least 11 codes in the book. There are also codes for a brake switch. Is this guy using a code reader or a scanner? There should be a code in memory in the pcm even if the light is not currantly on. But he has to look in the history part of the pcm.

Good luck
 
There are inputs to the PCM that may not be appear to be emission related such as the brake switch but in fact are emission related indirectly. Intermittent problems are hard to diagnose and the inputs on those years varies by chassis as some of the inputs were in the beginning stages of prepping for OBDII>. Truck chassis' had limited inputs on certain chassis and others had more depending on the GVW. Yopu need the manual or vbe familiar with that particular chassis. There were exemptions during those years. The ideal would have been all cars and trucks make the switych at the same time but it didn't happen that way.

Tom, Good Luck on getting it fixed. Sounds like the mechanic is on to something. I have seen alternators with bad diodes raise havoc with speed sensors and other electrical components even though GM did a great job of protecting tyhe ignition system from problem alternators. Hope it all works out for you. 
 
gwcowgill said:
There are inputs to the PCM that may not be appear to be emission related such as the brake switch but in fact are emission related indirectly. Intermittent problems are hard to diagnose and the inputs on those years varies by chassis as some of the inputs were in the beginning stages of prepping for OBDII>. Truck chassis' had limited inputs on certain chassis and others had more depending on the GVW. Yopu need the manual or vbe familiar with that particular chassis. There were exemptions during those years. The ideal would have been all cars and trucks make the switych at the same time but it didn't happen that way.

Tom, Good Luck on getting it fixed. Sounds like the mechanic is on to something. I have seen alternators with bad diodes raise havoc with speed sensors and other electrical components even though GM did a great job of protecting tyhe ignition system from problem alternators. Hope it all works out for you.
I already told him about the alternator. Diodes and rectifiers will play havoc with the electronics. I had this problem last year. All the info I could find on the GM chassis was the change over years was 95/96. I have a early 95 chassis, and my buddy has a late 95 chassis in a 96 Storm. His has the obd1 system but obd2 port. His snap on scan tool won't talk to his coach through the obd2 port because it is obd1, but my Mac will.
 
92GA said:
I already told him about the alternator. Diodes and rectifiers will play havoc with the electronics. I had this problem last year. All the info I could find on the GM chassis was the change over years was 95/96. I have a early 95 chassis, and my buddy has a late 95 chassis in a 96 Storm. His has the obd1 system but obd2 port. His snap on scan tool won't talk to his coach through the obd2 port because it is obd1, but my Mac will.
That's right. '95 was the 1st year for OBDII for passenger cars & light trucks. Medium duty trucks remained OBDI until '96 then it depends on the weight. My '98 Winni ('97 chassis), has no OBD port at all because it's over 14K#.
 
The mechanic put the new brake switch in and then we took it for a drive. It did not solve the problem. He drove it a long way and played with the OBD1 reader a lot. He discovered the problem is definitely in the transmission. When it downshifts into second gear the output of the trans reads 0. The problem does not happen when it is cold, only when hot. It does not happen when accelerating, only when decelerating. The fluid is just fine. It is not light brown, but a dull pink and has absolutely no odor. He is researching the issue right now.
 
SeilerBird said:
The mechanic put the new brake switch in and then we took it for a drive. It did not solve the problem. He drove it a long way and played with the OBD1 reader a lot. He discovered the problem is definitely in the transmission. When it downshifts into second gear the output of the trans reads 0. The problem does not happen when it is cold, only when hot. It does not happen when accelerating, only when decelerating. The fluid is just fine. It is not light brown, but a dull pink and has absolutely no odor. He is researching the issue right now.
If it were in my shop, I'd have them pull the pan and inspect for metal in the pan. Install a new filter and try it again.

Have you ever had a trans flush on that rig? If it were me, I would not let them anywhere near it with a flush machine unless they changed the filter before and again after. If the filter has not been changed in a long time or if it has particles in it, the flush machine could dislodge material and force it into the valve body. By changing the filter 1st you eliminate that possibility. By changing it again after, you remove anything that may have been floating around in the torgue converter (and placed in the new filter) and you start with a clean trans.
 
The final decision by the mechanic is that I need a new transmission. He is a fairly honest guy. He put in at least six hours troubleshooting it and only charged me for two hours. A rebuilt tranny installed would be $3000. That may sound like a disaster but it isn't at all. I left Disney World headed for Denver. I was going to park there and start saving for a newer RV. I want one about 3 foot longer with more room in the kitchen. This RV has too many problems so rather than fix it I was going to get a newer one. I was going to stay in Denver until fall and then head to Phoenix for the winter.

So what I am going to do now is find an RV park in the Kissimmee area and stay here and save my money instead. If I had driven to Denver and Phoenix it would have cost me well over $1000 in gas and I would have had to tune it up and put new tires on it to make the trip. So that is $2000 I won't have to spend. When I go to sell my RV I will probably be taking $2000 less so it appears to be a wash to me. Providing nothing happened to me on the way out west. There are billions of birds here to shoot so I am not exactly in bad shape. Don't feel sorry for me. I got my moneys worth out of this RV, now it is time to save and move on up to the next one. I am guessing I will be looking at RVs between $10k and $20k so it will take me six months to a year to save up the cash since I don't do credit. Meanwhile I hope no hurricanes come along...

The cool thing is I will be living only a few miles from Catblaster and his lovely wife Jane so I do have some friends in the area.
 
With what you have posted so far, I cant see how it can be the transmission. They are not all that complicated.  As long as it doesnt slip(clutches worn out) or the torque converter hasnt failed(locked up), pump has failed(wont go), there isnt much else to go wrong with them.

Paul
 
It is definitely the tranny. When the RV is downshifting the output from the trans reads zero rpm when it shifts into second gear. The light then comes on and the speedometer goes wild. The trans has an input and an output sensor that are identical. So he swapped them and the symptoms changed, so he replaced the output one and that didn't solve the problem. He spent at least two hours driving it with the OBD1 computer reading codes. He is not trying to sell me a transmission. He told me point blank it was not worth the money to put a new tranny in. He even told me I could drive it like it was. Not exactly high pressure. The problem is no one is coming up with a better idea. I have searched the Internet and listed my problem on two different forums.

Bottom line is I will be happy here in Florida for the next year or so. And I will happier with a newer RV.
 
SeilerBird said:
It is definitely the tranny. When the RV is downshifting the output from the trans reads zero rpm when it shifts into second gear. The light then comes on and the speedometer goes wild. The trans has an input and an output sensor that are identical. So he swapped them and the symptoms changed, so he replaced the output one and that didn't solve the problem. He spent at least two hours driving it with the OBD1 computer reading codes. He is not trying to sell me a transmission. He told me point blank it was not worth the money to put a new tranny in. He even told me I could drive it like it was. Not exactly high pressure. The problem is no one is coming up with a better idea. I have searched the Internet and listed my problem on two different forums.

Bottom line is I will be happy here in Florida for the next year or so. And I will happier with a newer RV.
You can get low oil pump pressure if the filter is plugged or the filter seal in the valve body is cracked (sucking air)....... just sayin'..... ;)

However, chances are the clutch pack seal is blown (judging by your original description).

Worst case scenario....... pull the trans and have it resealed and new fiber clutch plates (probably $500-$600 labor and a $200 O/H kit http://www.summitracing.com/parts/ati-406330?seid=google&gclid=CPLVn7eqyLUCFQxxQgodFyEAcA ). You'd be out less than a grand. If it hasn't had problems and no metal in the pan, there's no way that I would give that trans up for an unknown rebuilt. There is no way that I would destroy the trans by driving it with low oil pressure either.
 
Did he give you price on replacement or have it pulled and sent out for rebuild. What is worst case if you keep driving it like it is? At least you don't have to drive far to get home ::)
 
The price is for a rebuilt trans ordered from GM. I have no intention of keep on driving it. If I do it might quit on me out in the boonies then I would have to find a place to get it fixed. If I stay here I can pick and choose a good place to stay that is close to friends.
 
captsteve said:
Well, all will work out for the best. Let me know if you get bored, Trina and I might have to come visit.
I will definitely be hoping you two will come down for a visit. Plan on it when you get off the ship in March. I am hoping to find an RV park close to water so there will be a lot of birds in the area.
 
Wavery said:
You can get low oil pump pressure if the filter is plugged or the filter seal in the valve body is cracked (sucking air)....... just sayin'..... ;)

However, chances are the clutch pack seal is blown (judging by your original description).

Worst case scenario....... pull the trans and have it resealed and new fiber clutch plates (probably $500-$600 labor and a $200 O/H kit http://www.summitracing.com/parts/ati-406330?seid=google&gclid=CPLVn7eqyLUCFQxxQgodFyEAcA ). You'd be out less than a grand. If it hasn't had problems and no metal in the pan, there's no way that I would give that trans up for an unknown rebuilt. There is no way that I would destroy the trans by driving it with low oil pressure either.
Thanks for the suggestions but there is no way I am putting another grand into this thing. It also needs tires, shocks, brakes, springs and tune up. It is just not worth the time or money.
 
Tom,  from what you are saying, 1. It sounds like you are describing a 4L80E transmission with an input and output speed sensor. 2. When you step on the brake pedal the brake switch tells the transmission to stop coasting and allow engine braking. 3. It actually souinds like you may have a PCM problem that may be causing your problem.  I just ran a description of what you are experiencing and my son agrees that there very well be nothing wrong with your transmission.
 
The 4L80-E is able to handle vehicles up to 8000 lb
The 4L85-E is able to handle vehicles from 7200 to 16,500 lb
So I am guessing it is an 85. What is a PCM problem?
 

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