1998 Dodge Ram 1998 Dodge Ram CRUISE CONTROLL

Do you have a light on the dash the says "Cruise" when the cruise control is turned on? If you do, and it's not turning on, the most common cause is a broken clockspring under the steering wheel. If I'm right, eventually the horn will stop working and the "Airbag" light will come.

Caradiodoc

Do you mean there is not a "Cruise" light on the dash or there is a light but it's not turning on? Does the horn work?

Clockspring

There are two wires in the ribbon cable for the cruise control. All switches feed varying voltages through those two wires. That's how the engine computer can differentiate up to 6 commands with just two wires.

You can safely measure for continuity with an ohm meter at the connector under the steering column. The 9 volt battery in many meters is strong enough to set off the air bag if you measure between the wrong wires, but there is a shorting bar built into every connector in the air bag system to prevent this accident.

Woops, looks like the connector plugs into the bulkhead connector near the firewall. Each corner of the plug has a 3 x 3 group of pins. Disregard those. Of the four groups of pins next to the center bolt, two groups have four big terminals. Disregard those. The two remaining groups are 3 x 4 pins. Pins # 26 and 29 are in the center two rows toward the center of the plug. The wire colors are Black with a Light Blue stripe and Red with a Light Green stripe. They're both 22 gauge wires, about as small as it gets.

If you measure between these two wires, normal resistance is 909 ohms when the "On" button is pressed, 6650 ohms for "Set", 15,400 ohms for "Resume", 0 ohms for "Cancel", and 2940 ohms for "Coast". If any of these values are correct, the clockspring is ok. My educated guess is you will read infinite, (open circuit) for all switches. If some switches produce the correct value and some do not, suspect a cracked circuit board that the switches are mounted on. Found one of those once, but I suspect it was from rough handling when someone replaced it.

The 12 volts to run this system comes through a contact in the brake light switch. If that contact is corroded or pitted, the cruise won't set, but I don't know if the dash light will turn on or not. Once the system is fixed, try turning the system on while holding the brake pedal down, then you'll know for future reference.

I just remembered too, the air bag wires do not go through the firewall connector. That pair of wires go through bright yellow connectors. That's the ones with the shorting bars. If you leave them alone, you should be fine.

Holler back with your findings.

Caradiodoc