This is a very weird problem. I have searched the Internet and can't find an answer. The rig is a 1994 Damon Challenger class A RV with a 454 engine. I was driving along at 50 miles per hour when the Check Engine Soon light came on and the engine appeared to go out of gear and rev up a bit. But it was only a momentary thing and returned to normal operation immediately. However this kept happening about once ever 15 seconds. So after about 3 minutes of this I pulled over and call my roadside assistance people and was towed to a nearby shop.

They suspected the tranny and found the tranny was 2 quarts low on trans fluid. After putting in the trans fluid the tranny ran normally and didn't shift out of gear.

Now the weird part starts. Now the Check Engine Soon light comes on when I push the brake pedal about half way down when driving to a stop. Once I am at a stop pushing on the brake pedal will not make the light come on.

But wait, it gets weirder. When the Check Engine Soon light comes on the speedometer starts pulsing wildly.

And now it gets even more weird. This is an OBD1 engine. The mechanic plugged in the code reader and got no codes. He got no codes with it sitting in the shop. He took it out for a drive twice. Both times the light comes on and both times there are no codes involved.

I have read all the posts I can find on the Internet concerning the light coming on when braking and in every single post the suggestions are different and in no case does anyone ever post that they actually found and solved the problem.

RV mechanics charge about $100 an hour. I really don't want to take it in and ask them to solve the problem because they are just going to be trying random fixes that probably won't solve the problem. And yes, the gas cap is relatively new and screwed on tight. The engine oil reads full.

Does anyone have a clue???

 

It sounds like you have a vacuum leak, open the hood and have a listen while someone else hits the brakes.