Installing the Rostra Cruise Control (Kit # 250-9604) in a 2008 Nissan Sentra

These are my notes, tips, and thoughts from a successful install of a Rostra cruise control. This cruise control kit is specially designed for this car, as it has custom wiring harnesses. There are custom harnesses for many, many other cars as well.

If you are unfamiliar with this specific kit, it contains a control module which is the heart of the cruise control. It's a little bigger than a pack of cigarettes. There is a control switch assembly, which looks like a turn signal lever (but does not actually move). The kit also contains three wiring harnesses: one plugs into the gas pedal, one plugs into the OBD-II port, and one plugs into the control switch assembly. Finally, there are only three loose wires: red for power, black for ground, and one that's either white or yellow, depending on if you have a manual or automatic. And that's all there is to it. Now, it's not necessarily easy to install, but it's not really that complicated. I'd rate it somewhat more difficult than installing a radio, but not much.

The instructions are pretty straightforward and I skip the bulk of that information, since I don't need to reiterate it here. What follows are just some things from my experience that I note to help your install go smoother.

Remove lower dash for easier access

The first thing you'll want to do is to remove the lower part of the dashboard for better access. There is one Torx-15 screw located behind the hood release lever. Remove that screw and also remove the hood latch cable from the lever. You will also want to remove the OBD-II port which is located on the bottom of the lower dash, directly below the steering wheel. It is held in place with snaps. You may need to reach around behind the dash and pinch the OBD-II to get it to release.

The dash is now held in only by snaps. Pull it firmly toward you to remove.

Behind the removed section of dash there is a black heat/air duct. It is held in with one screw. Remove the screw, and the duct should come out simply by wiggling it.

Now you have about as much access under the dash as is possible.

If you have a manual transmission, skip the next section

For Automatic Transmission Only:

If you have an automatic transmission (including the CVT), the first (and I think most difficult) connection is to run a wire to the Neutral Safety Switch (NSS) which is located in the engine compartment. The kit includes a wiring harness with a yellow wire and a white wire. You need the yellow wire for automatic transmissions. The instructions say to cut off the white wire, and use it to extend the yellow wire which needs to run through the firewall, into the engine compartment. Don't do that. Get a long piece of 20-gauge wire and use that.

First, cut and bend a coat hanger so it's straight. I think it's a good idea to file one end so that it is rounded, so that it will not catch or cut and wires while you push it through the firewall.

Above where the clutch pedal would be, you will see a large bundle of wires which runs through the firewall. Insert the coat hanger between the bundle of wires and the rubber grommet. It may take a bit of pressure, but push the hanger through until you're sure it's through the firewall.

In the engine compartment, this bundle of wires comes through the firewall behind the air filter housing, which is behind the battery. You should be able to see the coat hanger once it protrudes into the engine compartment. Back inside the passenger compartment, tape the wire to the coat hanger with electrical tape. Overlap the wire and coat hanger at least six inches. Start wrapping the tape at the end of the coat hanger and go "up". This keeps the tape from catching as it goes through the firewall. Now, lube the coathanger and first foot of wire with soapy water. This helps prevent the wire from pulling off the hanger as you pull it through.

Back in the engine compartment, pull the coathanger firmly and slowly until the wire appears.

Congratulations, this was the hardest part of the installation! Here's an image of the wire just after I got it through the firewall. This is inside the passenger compartment.

Of course, you still need to connect that wire.

You will need to remove the air-intake assembly which is in front of the battery. There are two plastic rivets that hold it in place. Pry the center section up to remove them. Don't lose them!

Remove the air intake, and you see a wire bundle and connector right below it, in front of the battery. You do not need to disconnect this connection.

To the left of the connector, the bundle of wires is wrapped with electrical tape and a plastic wire wrap. Remove the electrical tape, and you can expose the wires from the wire wrap. You need to connect the wire you pulled through the firewall to the wire which is pink with a black stripe (as per the instructions). I prefer fast tap or scotch lock connectors since you do not need to cut or strip the wire. Once connected, replace the wire wrap and then re-wrap with electrical tape. In fact, I prefer silicone tape (Xtreme tape is one brand) because it's heat proof and water proof.

The rest of the installation takes place inside the passenger compartment following the instructions that came with the unit. The wire you pulled through the firewall connects to the yellow wire from the two-wire harness. Cut off the white wire as it's not needed for cars with automatic transmission.

The Red Wire

The instructions tell you to connect the red wire on the cruise control unit to a 12v switched wire behind the dash. Note that the wire you tap into may not necessarily be red. On my car, I found a 12v switched wire coming out of the fuse panel. This wire is yellow with gray dots/stripes. There are actually two of these, I used the one on the left. Be sure to test yours to make sure the voltage is correct when the car is both running and when switched off. I tapped into it with a fast-tap. The red wire in the image below is the power wire that runs back to the "cpu" unit of the cruise control. In this image, the bundle of wires may have originally been wrapped with electrical tape which I removed to access the 12v power wire. Note that all 12v wires will run about 14v when the car is running, so if that's what your multimeter reads, that's fine.

Testing

Before securing anything and before mounting the switch assembly you'll want to road-test the unit. Be sure that all loose wires are out of the way of the pedals!

Notice that the wires from the switch assembly are not inserted into the connectors yet. This is because they will need to be routed through the hole you will drill in the steering column cover. For testing, DO NOT insert these wire ends into the loose connector ends yet! They don't come back out once you insert them, so you will not be able to route them through the hole later. Using the instructions as a guide, insert each wire end into the white and black ends of the wiring harness. They will be snug and not fall out. It's a good idea to wrap a piece of electrical tape around the exposed metal parts while you're road-testing this so they don't touch anything.

If everything works while road-testing, then you're ready to mount the unit and the control switch assembly.

Considerations

While wiring all this up and mounting the control module, don't forget that you need to replace the heat/air duct you removed for access. You don't want to get into a situation where you cannot replace the duct because of the way you routed the wires.

Also, for the wires that run to the gas pedal, be sure to run them up and over the clutch (if applicable) and brake pedals. Also, make sure no wires are touching moving parts from any pedals or the steering assembly. There is a thin wire bundle running above the pedals high up on the firewall. It's a good idea to route the gas pedal wires along this wire bundle with zip ties.

When ready to secure the control module and replace the duct, bunch up the cruise control wires, and fasten them to the bundle of wires that comes through the firewall above the clutch pedal (or where the clutch pedal would be) to keep them out of the way while driving.

I secured the control unit itself on the far left of the firewall, away from all moving parts. Just make sure it's secure and won't rattle as you drive.

Finally, the red power wire contains an in-line 1 AMP fuse. You will probably have ample excess wire that you can route the red wire such that this in-line fuse is located near the fusebox (which is behind the coin tray). Placing the fuse in this accessible spot will make it easier to replace the fuse later, should you need to, without having to crawl around under the dash.

Mounting the switch assembly

There's really only one place to mount the switch assembly, and that's just below the blinker lever as seen in the picture. Unfortunatly, it's difficult to see the unit when it's mounted here because of the configration of the steering wheel. Of course, after just a couple of times using the controls, you won't need to actually see it.

Be sure to mount the switch assembly so that it does not interfere with the blinker lever or the tilt-steering wheel lever.

Before removing the steering column cover, use a pencil or marker to mark the spot where you'll be drilling. It may get confusing after the cover is removed, and marking it first prevents mistakes like drilling on the wrong side of the cover.

There are three screws recessed on the bottom of the steering column cover. Remove all three. Then, insert a flat screwdriver between the blinker lever and the top of the cover as seen in the picture below. Gently pry the top and bottom halves apart, they are only snapped together at this point. Do the same on the other side.

Remove the lower half of the steering column cover. Lowering the tilt steering wheel lever helps a little. Drill the hole where you marked. Route the wire as in the instructions and secure tightly with the nut.

Replace the steering column cover, making sure the wire is routed where it doesn't interfere with anything in the steering column.

Once the cover is replaced, NOW you can insert the wire ends into the loose connectors. Double check the correct positioning, because you only get one shot. Once the wire ends are inserted, they don't come out.

And, that's about it. Once you plug in the harnesses and mount the control module, you can replace the heat/air duct, and then the lower part of the dash, and you're done. Remember that the wiring harness that plugs into the OBD-II port actually becomes the new ODB-II port which you snap into the lower part of the dash.

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