nfrantz007

About a month ago I was cruising along on the interstate with the cruise control on and turned my turn signal on to change lanes. The CC disengaged as soon as the turn signal went on. I tried it again and it did the same thing. I also noticed when the turn signal light on the dash flashed the engine would rev 300-400 rpms and return to where it was.

It only does this (or is only noticeable) when the truck is in o/d...

Any thoughts on what would cause this? Is there a link between the turn signal and the throttle or one of the throttle position sensors? bad relay? fuse?


Thanks!

nfrantz007

no thoughts?

has to be a TPS interference / going bad right? Since these things are not drive by wire.

The only thing I can think of is to start checking for a bad ground or wire. Then start replacing things: left hand controls, TPS....

Beto

It's an automatic, right? By overdrive you don't mean 5th gear?

Some of the 4runners are drive by wire (like mine), but they do it differently than any other manufacturer that I'm aware of. If it is 3rd gen, 2002 with VSC then it is drive by wire (some others too but I don't know all the years) but there is a cable running from the pedal to the Throttle body, the accelerator position sensor is built into the throttle body, and there is a motor built in that the ECM powers to control the butterfly. You can find out for sure by pulling the intake off and opening the throttle all the way with the engine and key off, if it's drive by wire then the butterfly will only open a small distance, turn the key to ON and it will open all the way.

Your specific problem sounds more like the torque converter lockup clutch coming disengaged and then reengaging. It'll cause about 200 - 500 RPM change with no change in vehicle speed when the torque converter starts to slip again. This clutch is electrically controlled by a solenoid connected to the ECM - and only activates in OD, when the vehicle is not accelerating heavily. It's purpose is to save fuel (and it also stops the heat generation by the torque converter). Any significant change in throttle will disengage the clutch.

If you are going to start looking and replacing stuff- I would not include the TPS in that initially. It sounds like bad ground or power feedback from the turn signal - or an ECM.

I would start by verifying all the turn, stop, and parking signals and lights - make sure that they all look to be working normally.

Next, if you have the tools and ability, I would try monitoring the torque converter lockup clutch solenoid signal from the ECM, to make sure that the ECM is really telling it to turn off, then go from there.


Hope this helps.


edit: if you can recreate the symptoms in any way other than the turn signal - also, is the problem consistent and predictable or intermittent? Try lightly applying the brakes just enough to disengage the cruise - see if the RPM thing happens, try pushing the Cruise cancel, see if same thing happens, try pushing Cruise On/Off, etc...

Also, try the Hazard lights, on an '02 they are on a different fuse than the turn signals - and the horn, it's on the same fuse as the hazards. Post the year and model of your truck and maybe there will be better, specific info for your truck. - I see in your sig now '97.

nfrantz007

Interesting...

My hazard lights have been acting up lately (the switch will come on and off (the light) and they don't always work), I'll pull the dash and make sure the switch properly plugged in and replace it if is the problem. If not I will start checking for a bad ground somewhere.

Hopefully that will fix the problem.

TheDurk

Just a quick thought: in my experience, the weirder the symptoms and the more systems involved, the more likely the problem involves a faulty ground somewhere. Grounds used to be the last thing I thought about, on weird ones it is now the first. Think especially about any recent work (in the last year) where something got loosened up that may have had a ground strap attached and not re-tightened fully. These can be a real b***ch to track down.

Beto's suggestions all have merit. A cleanup on the tranny connectors might help. They are close to the road and get more water and crud exposure than most. Did you do any water or mud intensive off-roading just before this problem started?

nfrantz007

Blown third break light. Problem fixed.

quicksilvr

That thing causes more problems than it's worth sometimes.


I just saw mine was dead, so I replaced it, even though nothing strange was happening. Seems odd that if it has the ability to do stuff like it did to you, it doesn't automatically do it every time.