98 sienna involuntary acceleration

[sienna1998]

Hi all. This only happens when at, or very near to, a complete stop. When beginning to accelerate the engine surges, adds about 1000-1200 rpm for 2-2.5 seconds then is fine and returns to normal. Applying the brake will hold the rpm high indefinitely. The only way to stop it is to hold on till it finishes or slip the transmission into neutral. Since the vehicle is now rolling along, placing the transmission back into drive you can continue on as if nothing happened. The gas pedal does not pull away from underfoot. At all other times the van runs great. There are no OBDII codes showing up. None.

My local dealer shop, New Westminster Toyota in BC, Canada, refuses to diagnose the problem and wants to replace parts until its fixed and have me pay for it all regardless of the replaced parts value to fixing the problem. Any high school student can do that. They will never see me again.

Checked out a Haynes manual from the library. Replaced the Throttle Position Sensor. Completed the diagnostic test in the manual for the Air Intake Control and it operates fine.

I want to remove the fuse for the cruise control but the manual does not show where it is or how it is labelled. Just says there is one. I've looked at the lid for the fuse box in the engine compartment drivers side but TLA's (three letter acronyms) are not understandable without a legend and the manual doesn't explain them.

Any help here would be greatly appreciated. I'm sure you can appreciate the dangerous situation this is.

btw I've been buying parts from Rockauto.com The prices vs retail here in Vancouver is 30% to 70% less. I pay $13 a year for a mailbox in Blaine Wash and have been through the border 3 times with parts value up to $173 and have not been asked to pay BC 12% taxes. A very good deal.

[wiswind]

That is a strange problem.....I'm wondering if it is transmission related or Idle Air Control (IAC) valve related.
The throttle is a cable from the accellerator to the throttle body.
The cruise control "should" not be involved at this point......If it was on, it should disengage when your speed drops by 20mph or more, so that you have to reset the cruise speed.

[sienna1998]

thanks for the reply. Yes, I've been told it's strange by a couple of garage hobbyists. I'm aware of the linkage which is why I mentioned that the pedal doesn't pull down at all during this. The diagnostic procedure in the Haynes manual for the AIC results in a good test.

The reason I'm looking to remove the fuse for the cruise control circuit is simply to eliminate the possibility. An rpm increase of that amount is quite significant and as we all know electronics in vehicles can do some very strange things at times.

Any idea which fuse?

[wiswind]

I found 4 fuses involved in this.
The one that I think you want is in the fuse/relay panel that is inside the vehicle, driver's side, by the driver's left knee in the bottom of the dash panel.
It is Marked "ECU-IG" and is 15A