Toyota Tacoma Transmission Headache

My 2002 Tacoma has recently been experiencing transmission trouble. Between 45-60 MPH at various revs, the truck begins to shudder and shake. The severity depends on how aggressively I accelerate. After several weeks of this, the check engine light came on. It has remained on since, except when it flashes if I accelerate too quickly. Throughout the shuddering, the revs remain constant. By roughly 60-70 mph, the truck runs smoothly again. In a (possibly) unrelated note, the parking brake indicator is lit almost constantly, particularly in wet or cold weather, although the brake is not engaged.

Holy cow. Check your brake fluid before you drive again. That brake indicator light also tells you if you’re low on brake fluid.

Your “transmission” headache is probably an engine issue. Do not drive the truck with the check engine light flashing. That light means that there are error codes stored in the computer. Flashing is very often a severe misfire. This will be an issue with spark, fuel, air supply, and/or compression. But you need the exact error codes. Many auto parts stores read these codes for free. Have them read and post the exact codes - format: “P1234”

Also give all the rest of the info on the vehicle - mileage; complete run down of maintenance, and be specific about it (plugs, wires, filters, transmission services etc.)

Also, if your brake fluid is low, the calipers may have collapsed and the pads are rubbing on the disc. It is possible that the shuddering is related tho this. But it’s hard to tell without riding in your truck.

The brake fluid is perfectly fine (unfortunately?..I thought that might be a quick fix.) Could a misfire be taking place within such a narrow power-band? The shudders only happen for about 1-3 MPH before dissipating; I feel like misfires or air supply problems could affect the engine at any time, or even the whole time I am driving.

Misfires most often occur under “load” conditions. Often on accelerating in a higher gear. Last time plugs were changed? This is a coil on plug set up I believe. You could need new “boots” on your coils, the rubber rubber in the boots can get old, hard, and allow arching to ground causing the misfire. If it happens enough it will take out the coil. Boots are cheap, new coils are more expensive.

A flashing check engine light is telling you to stop driving the truck NOW.

At this point, anything could be going on and you haven’t said much more about any of it to move people forward. So, could the engine be doing something funky under the conditions you describe? Sure. Could the transmission? Sure. But you also have to see the engine and transmission as completely tied together - a small engine management issue (e.g. throttle position sensor) can send your transmission nutty…stuff like that.

So just get the codes and post them along with the maintenance history info.

I agree it sure sounds like a misfire. That check light should tell you which cyl is having the issues. Step one is pull that plug, see what it looks like. Step two is to move the coil to another cyl and see if the misfire follows the coil.

I would first tackle that engine misfire issue and see if this alleged transmission issue disappears with the misfire. Flashing check engine light = serious misfire, and yes, it is very common for people to mistake an engine performance problem for a transmission problem. Even my sister has done this, and she is more car savvy than most men. My chief suspect for the misfire is carbon tracking on either the coil or the boot. This can cause an intermittent, but serious, misfire, and the best part is that it is easy to fix.