1996 Dodge Ram No cruise P1683 code

Tiny
BR4X4
  • MEMBER
  • 1996 DODGE RAM
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 127,000 MILES
Hello, cruise has not worked for a while and I have spent many hours trying to fix but to no avail. I have snapon scanner and got a code P 1683, how can I fix this?
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Tuesday, March 9th, 2010 AT 7:43 AM

26 Replies

Tiny
CARADIODOC
  • EXPERT
This code refers to the speed control servo power circuit open or shorted. The power comes through a normally-on contact in the brake light switch. Use a test light or voltmeter to measure the voltage on the yellow wire / red stripe on the switch. If it's there, measure on the dark blue wire / red stripe. If it's missing there, the switch is defective. The voltage should go to 0 volts there when the pedal is pressed.

Caradiodoc
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Tuesday, March 9th, 2010 AT 3:39 PM
Tiny
BR4X4
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Thanks, I will check this today.
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Wednesday, March 10th, 2010 AT 6:46 AM
Tiny
BR4X4
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Hi when I checked today I got.09 volts to 0 volts.
What should be the correct volts at which wire and with
KOEO OR KOER.
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Wednesday, March 10th, 2010 AT 1:33 PM
Tiny
BR4X4
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I don;t think its getting volts to the switch.
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Wednesday, March 10th, 2010 AT 1:34 PM
Tiny
CARADIODOC
  • EXPERT
Sorry about that important detail. The engine must be running, then there must be 12 volts on both wires when the brake pedal is not pressed. It comes into the switch on the yellow wire with red stripe.

The 12 volts leaves the brake light switch and ends up at the servo on the dark blue / red wire.

Caradiodoc
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Wednesday, March 10th, 2010 AT 4:25 PM
Tiny
BR4X4
  • MEMBER
I am not getting 12 volts at the switch on either wire.
With engine running, or not.
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Wednesday, March 10th, 2010 AT 5:14 PM
Tiny
CARADIODOC
  • EXPERT
OK, that voltage comes from the Engine Computer, connector 3, pin 11. That's still a yellow / red wire. If it's missing there, check for some voltage on connector 3, pin 32. It's a red wire with light green stripe. The voltage will vary according to which cruise control function switch is pressed. If no voltage appears, suspect a broken clock spring under the steering wheel.

As an alternative, if there is a green "Cruise" light on the dash, the clock spring, on / off switch, and Engine Computer are working if the light turns on. Usually, when the clock spring breaks, it's not long before the horn also doesn't work and the air bag warning light turns on.

Caradiodoc
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Wednesday, March 10th, 2010 AT 5:39 PM
Tiny
BR4X4
  • MEMBER
Thanks for your help. I changed the clock spring
about 3 times in 5 months. That is not the prob.
The switch is showing the green light when on. The switch is also new. As is the intake heater grid soleniods
my snapon scanner will operate all relays and soleniods.
And I can hear them work. The cruise just stopped working one day and I am stumped. Maybe all grounds should be cleaned. But if that was the case other things would not work.?
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Wednesday, March 10th, 2010 AT 6:23 PM
Tiny
CARADIODOC
  • EXPERT
Hold the phone. The green light is on? Dandy. Things are working up to the Engine Computer. Recheck the voltage at the brake light switch. If you still find 0 volts, double-check the ground for your meter. If you feel confident there's no voltage there, check at the wire in the Engine Computer's connector. If it's missing there, suspect a problem inside the computer. If voltage is there, look for a break in the wire from there to the brake light switch.

Caradiodoc
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Wednesday, March 10th, 2010 AT 7:36 PM
Tiny
BR4X4
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Hello, thanks for helping me. Today I checked the brake
switch and with the test light I got power at y/r wire and dark blue wire and when I pressed pedal it cut off power, so the switch is good. Where should I go to next.
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Saturday, March 13th, 2010 AT 1:23 PM
Tiny
CARADIODOC
  • EXPERT
Check for 12 volts on the same wire at the cruise control servo. If you can't find it, follow its throttle cable from the throttle body. It will lead you to the servo near the battery. The servo will have a four-wire plug. Back-probe the dark blue / red wire. If there's no 12 volts, there's a break in the wire between there and the brake light switch.

If you do find 12 volts, also check on the tan / red wire and the light green / red wire. There should be 12 volts there too. Don't use a test light on them if the engine is running as they could cause the engine to go to wide-open-throttle. Finally, check for voltage on the black wire. If you find any voltage there, the ground wire is open, either in the wire, or more likely, where it is bolted to the body.

The last three wires must be tested while still plugged into the servo, otherwise their voltages are meaningless.

Caradiodoc
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Saturday, March 13th, 2010 AT 2:47 PM
Tiny
BR4X4
  • MEMBER
Thanks for helping. OK today (Sunday) I probed the
connector from the back, got voltage on all three. And no volts from the ground.
I am losing the little light as I start to drive. Cut truck off and start again I get light and then gos out. Sitting in
driveway start truck got the light and can probe connector until it goes out again. I am satisfied with all 4 wires in that plug they are fine. Where to now.

1996 Dodge Ram 2500 Cummins Turbo Diesel, Auto Trans, 128000 miles, 4x4. Reg cab long bed. SLT.
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Sunday, March 14th, 2010 AT 12:25 PM
Tiny
CARADIODOC
  • EXPERT
Are you referring to the test light at the servo connector or the green "cruise" light on the dash?

If the cruise light goes out, can you turn it back on and off by pressing the button on the steering wheel?

Caradiodoc
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Sunday, March 14th, 2010 AT 1:53 PM
Tiny
BR4X4
  • MEMBER
Yes I am talking about the little green lite on the steering wheel. No, not able to turn it back on going down the road. Now in the driveway I can shut it off
start it back up and then the lite will come back on.
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Sunday, March 14th, 2010 AT 3:54 PM
Tiny
CARADIODOC
  • EXPERT
Confused. "Not able to turn it back on" but you can shut it off?

If you can not cause the light to change with the switch on the steering wheel, back-probe the red / light green wire in connector # 3 of the Engine Computer, pin 32. The voltage should vary depending on which switch is pressed. Typically, if a wire is broken, there will be 0 volts there regardless of which switch is pressed. If you find some voltage when the "Resume" or "Cancel" buttons are pressed, the wires are good. If you find pressing the "On" button results in the same voltage as one of the other buttons, there is a problem with the switches. The computer determines which function was pressed by the voltage that appears on that wire.

Caradiodoc
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Sunday, March 14th, 2010 AT 5:22 PM
Tiny
BR4X4
  • MEMBER
I am sorry for all the confusion. The little green cruise light will come on when I press the on/off button on the steering wheel, now when I start to drive down the road it will cut out and will not come back until I stop the engine and restart engine, then the little green cruise light will come on shortly then cut out.
Not able to back probe the connectors at PCM because of way connectors are made, ( sealed). My service manual says circuit V37 at PCM cavity 32 has 5.0 volts
when on/off switch is open. 1.51 volts when it closes.
V37 is rd/lg wire from speed control switch signal at PCM
C32. V32 is YL/RD WIRE from C11 at PCM it is speed control feed. It supplies voltage to the little green cruise light and switches at the steering wheel.
Sorry for the long post.
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Sunday, March 14th, 2010 AT 6:33 PM
Tiny
CARADIODOC
  • EXPERT
My manual shows the V32 circuit drawn two different ways on two adjacent pages. It doesn't show the green light, but the voltage has to be coming from the PCM and going to the brake light switch, then to the servo. To double check me, press the brake pedal to open the switch, then there should be voltage on the yellow / red wire. If you find 0 volts, and voltage on the dark blue / red wire, I'm looking at it backwards.

Also, if I'm wrong, there will be no voltage on either wire if the servo is unplugged.

You're right about the yellow / red wire to the switches. I was looking at it as supplying voltages to the PCM, but in fact, the 5.0 comes out of pin 32 of the PCM and is grounded by the switches. Can you monitor the voltage on that wire from under the dash? Does the cruise kick in while the green light is on?

I'm wondering if there's an intermitent break in the clockspring or two circuits are touching at the ends of its ribbon cable. It almost sounds like the PCM is detecting a problem and is shutting the system down in response. That could be due to the detected problem could lead to it going to wide-open-throttle, or the problem could prevent it from getting the cancel signal from the control switch or brake light switch.

Caradiodoc.
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Sunday, March 14th, 2010 AT 7:43 PM
Tiny
BR4X4
  • MEMBER
On my truck you press the on/off switch on the steering wheel, the little green cruise light comes on.
Now the servo takes the throttle when you press set/cruise switch.
The brake light switch works like you said in early post
y/r wire is hot, d b/r wire is hot until you press pedal.
Db/r wire goes to servo from brake pedal switch.
OK at the servo plug: V36 TN/R wire is S/C vac Sol contrl
V35 LG/R wire is S/C vent sol. Control. Blk. Wire is grnd.
V30 DB/R wire is s/c on/off switch output.
Clockspring is new.

-What does the inside of the servo look like. Could it be shorted to ground and the PCM shuts down the whole system.
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Monday, March 15th, 2010 AT 8:38 AM
Tiny
CARADIODOC
  • EXPERT
If you remove the two tiny screws on the connector cover, you can slide the coils out. There are three coils soldered to the circuit board that the connector pins are soldered to. Had one warranty unit the had a broken wire right on the end of the coil of wire where it was soldered to the terminal. Resoldered it and had a good working servo.

There's tiny rubber pads that open vacuum passages. They are controlled by the coils.

Do you see a change in voltage on the red / light green wire from the steering wheel switches while driving?

Caradiodoc
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Monday, March 15th, 2010 AT 2:32 PM
Tiny
BR4X4
  • MEMBER
OK the green cruise light on the on/off switch on the steering wheel, will stay on only for 30 seconds to 1 min.
And only when I stop the engine and restart the engine will I get the green cruise light again for 1 min.

The servo is 60.00 at the dealer. I do not want to buy this if the other is good.

The green cruise light staying on for 1 min. Is the key to
solving this problem I think.

I am going to tie in a new ground wire to the servo plug and see what happens and I will get back to you soon.
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Monday, March 15th, 2010 AT 3:24 PM

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