RPMs increase when blinker turned on

[Fordtilitdies]

1994 Ford Explorer. When I turn on the blinkers, wipers, roll down the window, and even turn the steering wheel, the cruise control disengages or slows down. I originally thought it was a cruise control issue but today I noticed that when I turned on the right blinker the RPMs increased up while I was doing about 65mph. I didn't noticeably accelerate but it seemed like the overdrive might have kicked off momentarily. Another possibly related issue is that when I am in park the RPMs will surge to around 2000 to 2500. Does anyone have any idea what might cause all of these problems if they are related? I have not checked alternator output, and the battery has been replaced since I first noticed that the CC was having issues.

 

[Jason94sport]

Vac leak, dirty MAS, throttle body or IAC. All easy to clean.

 

[FR-425]

The cruise control disengaging when you use (touch, wiggle, bump,) the turns or wipers is a bad turn switch: Very common $65 easy to replace.

The Crank Position Sensor is what is used for tach signal.

Is the engine actually reving 2500 in park or is it just the tach bouncing?

The erratic speed while on cruise would be The Vehicle Speed Sensor.

Is the speedo bouncing around?

 

[Sonofbumperbolt]

I had a Ranger that used to kill the cruise when I signaled a lane change. It ended up being the tail light wiring was botched from someone trying to wire a trailer harness into it.

 

[cgbier]

I had a Capri that shut down the complete electric for half a second when I switched to high beams. Was the signal switch, as FR-425 mentioned.

 

[FR-425]

I had a Ranger that used to kill the cruise when I signaled a lane change. It ended up being the tail light wiring was botched from someone trying to wire a trailer harness into it.

Yep, the trailer light relays and wiring can be an issue as well.

The reason is that the cruise is disengaged by brake light activation.

So if the PCM gets a signal that the brake has been applied = disengage. even if it's a bogus signal.

The brake pedal switch can contribute as well.

On my Ex I had all of the above. faulty trailer wiring, bad switch, goofy brake pedal switch, and dirty contacts in the steering wheel.

The actual cruise control device had no issues.

None of this is expensive to replace but it will take some time to get all the details sorted.

Here's Ford's entire trouble shoot for cruise in the first gens.

Pics are out of order but copy/paste print and you can make a booklet.

NOTES: Guide covers manual trans and automatic. i.e. auto trans will not have clutch dump.

NOTES: The dump valve is part of the speed control servo for auto trans. Or is near by connected by vacuum hose.

NOTES: Vehicle minimum speed for cruise is 40 mph. (in your case the VSS sounds wonky as well. I'd start there Test with multimeter 200-300 ohms as seen on last pic.

OH! ONE MORE NOTE ::VERY IMPORTANT.....STORED BRAKE FAULT CODES WILL PREVENT CRUISE ENGAGE! CLEAR THE COMPUTER AS YOU TROUBLE SHOOT. YOU WILL CAUSE FAULTS AS YOU GO.

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