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Chrysler Repair/speed control fault code 1596


QUESTION: Where is it located on a 2003 dodge grand caravan 3.8 and would it make the van run like it had a bad plug if something was wrong with it

The only speed sensor is the output speed sensor of the transmission which powers the speedo and also helps to operate the engine. If it were bad it could affect both. But try using the ignition key to get a fault code readout: 'on-off-on-off-on and leave on', doing that in 5 seconds of less elapsed time. Then watch the odometer window to see the mileage reading be replaced by a 4-digit number(s) preceded by a P. Let me know what you find.
Please read the PS below and respond to it.

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QUESTION: The code is 1595 I'm sorry I thought I wrote that

ANSWER: That code says that the problem is in the speed control servo unit, either the vent or the vacuum control solenoids' circuit. The servo has a 4 pin plug and violet/yellow wire on pin 1 goes to pin 56 of the powertrain control module, while the violet/orange wire on pin 2 goes to pin 80 of the same pcm plug. The code says the circuit is either shorted to ground or open. The other end of the each solenoid is grounded by a black/light green wire on pin 4 of the servo plug and goes to a common ground point located above the starter (on the engine block proper).
You can inspect the plug and its harness, and also verify the connections I listed for each of the three wires. The wire on pin 3 violet/white goes to the brake lamp switch under the dash on the brake pedal.
I doubt this issue would affect the running unless it happened only when you activated the cruise control.
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QUESTION: The car felt like it was only running on 5 cylinders and I changed the plugs and it is still doing the same thing any suggestions?

Hi Al,
Try removing the spark plug caps one at a time to see if one of them does not impact the idle. Then measure the compression on that cylinder to see if there might be low compression situation there.
Otherwise, keep checking for fault codes until one comes up.
About the only things that I know of that cause missing without, a code, are the egr valve being stuck slightly ajar or a vacuum leak on one of the hoses to the intake manifold. Check the egr valve by locating the stem (between the valve body and the vacuum operated round top-piece, hidden by a flange. There is a slot in the stem that you can use with the tip of screw driver to move the stem back and forth. Internal spring-action should be felt to close the valve to a dead stop. If it seems sticky/ajar then spray some WD-40 on the stem where it enter the body of the valve and exercise some more.
Look over all the vacuum hose connections on the hoses that attach to the intake manifold.
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Roland Finston


Free fast answer to your repair question about a Chrysler/Dodge/Plymouth car, minivan, SUV, or truck. Problems with electronically controlled engines and transmissions as well as body wiring problems are my specialty. This free troubleshoot advice forum helps you diagnose faults, minimize repair costs or do-it-yourself.

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