How Do I Know If Transmission Modulator Is Going Out?


4 Answers

Abi Ainscough Profile
Abi Ainscough answered
You will be able to tell if your transmission modulator is not working properly or is experiencing some problems if the transmission will not shift properly. This shows that the modulator valve is not working. This kind of problem could be caused by the hose that connects the transmission to the engine vacuum develops cracks, burns or begins to collapse in on itself.

Here are some instructions on how to test if your transmission modulator needs replacing. First of all, start your car and allow the engine to warm up to its normal functioning temperature. Once it has reached this temperature, move the transmission into the 'park' position and set your parking brake in position firmly. If you keep your car in the garage, make sure that the door is wide open when you do this, or that you have moved your car out onto a driveway.

Go around the back of your car to see what colour smoke is coming out of the exhaust. If it is blue then this is caused by a rupture in the diaphragm in the modulator valve which causes transmission fluid to be drawn up into the engine. When it is burned in the engine, the fluid produces blue smoke.

Using the instructions given to your in your car's owner's handbook, check the level of the automatic transmission fluid level. Your engine must be running to check automatic transmission fluid. A damage or ruptured modulator diaphragm will cause a significant loss of fluid.

Another way to test for a bad modulator valve is to drive your car, starting at a complete stop and then accelerating to 25mph and listening closely to the noise of the engine. If the transmission shifts much later than normal and the engine speed is too high then this is usually a sign of a bad modulator valve.

Listen to your car's engine for any unusual noises such as whistling or a rough and fluctuating idle speed. The whistling speed could show a leak in the vacuum line which can lead to modulator problems later on.
Anonymous Profile
Anonymous answered
You can tell when the modulator is bad because then the diaphram will be cracked and leak red ATF when you pull the vacuum line off.
mike carlsen Profile
mike carlsen answered
When the shifts become either firmer or softer from normal. Loose shifts could also be a sign of a clogged tranny filter, loose or worn bands or a worn clutch pack. Firmer shifts than normal are usually just caused by the modulator. I really don't like the modulator system, I like the old chrysler trannys better, they didn't have them and were very simple to rebuild ;)
care bears Profile
care bears answered
Hello,  My Husband said, that when it shifts hard when it don't want to pull that car

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