Adding cruise control to RENIX rigs (lots of pics)

[Airborne Janitor]

This documents the install of RENIX cruise control on my 89 MJ 4.0L AW4. Used this post for reference:

 

https://comancheclub.com/topic/55178-how-to-install-renix-factory-cruise-control

 

1) Contact @eaglescout526 and get one of his cruise control kits. He'll get you the right parts for your particular set up. The only thing extra you'll need is a new speedometer cable.

 

2) Part list:

 

SERVO

 

SPEEDOMETER CABLE (SHORT)

 

SPEED SENSOR

 

WIRING HARNESS

 

VACUUM HARNESS W/ RESERVOIR

 

VACUUM/TCC SWITCH BRACKET, BRAKE SWITCH (CRUISE CONTROL VERSION)

 

SPEEDOMETER CABLE (Crown 53006180), CRUISE CONTROL MODULE

 

TURN SIGNAL LEVER (STALK) aka MULTIFUNCTION SWITCH

 

CLUTCH SWITCH (for manual trans)

 

 

[Airborne Janitor]

3) Remove your old speedometer cable. Start by removing the transfer-case end first. 

 

 

You may have a little bracket attached to your driver side UCA bolt that needs to come off too.

 

 

Pop the grommet on the firewall behind the instrument cluster

 

 

There's a million write-ups on here on how to remove the instrument cluster, so I'm not going to go over it. But the instrument cluster does need to be removed in order to fully remove the old speedometer cable.

 

4) Install the servo

 

So there are a few different types of servos out there, depending on your year, engine, and transmission. For the 4.0 I found there are two types of brackets to mount the servo.

 

TYPE 1: Bracket/servo mounts near the passenger firewall, near the coolant tank. This uses an L-shaped bracket that faces INWARDS towards the servo.

 

TYPE 2: Bracket/servo mounts in the middle of the firewall, behind the valve cover. This uses an L-shaped bracket that faces OUTWARDS away from the servo.

 

I got a TYPE 2 bracket which worked out great for me, because I have an aux fuse panel mounted where the TYPE 1 bracket would need to go. 

The bracket is removeable from the servo, which makes it easy to use it as a template to mark the 3 holes that have to be drilled. You can use 3/16 self tappers to install.

 

 

Route the servo cable under the MAP sensor bracket, and snap the cable end into the square hole on the throttle bracket. 

 

 

Clip the end of the cable into the "ball joint" on the other side of the throttle cable.

 

 

 

 

 

 

 

[Airborne Janitor]

5) Install new speedometer cable

 

Route the cable into the firewall first. Orientation of cable dictated by the rubber firewall grommet, and the smaller nut goes towards the instrument cluster. I had a hell of a time getting the grommet to install, and ended up having to cut a little off the lip to get it to fit.

 

 

Install the speed sensor onto the speedometer cable, then the shorter speedo cable onto the speed sensor (if it wasn't already installed).

 

 

Route the speedo cable through the inner firewall (there's a slot it goes through) and clip it into your instrument cluster. Reinstall instrument cluster. 

Install other end of speedo cable to the transfer case.

 

 

I reused the UCA bracket from the old cable.

 

 

Use zip-ties to secure the slack out of the speedometer cable and keep it from any moving parts (driveshafts)

 

6) Install cruise control wiring harness

 

Take a look at your entire harness. It's kind of daunting at first, until you realize where everything goes.

 

 

 

Remove the plug that's above the speedometer cable (hole) on the firewall, this is where you'll be routing the wiring harness through.

 

 

Starting from inside the cab, shove the harness through that hole servo connection end first. Look at the orientation of the grommet too.

 

 

 

 

 

 

 

[Airborne Janitor]

7) Install servo connections.

 

Take the wiring harness you just pushed through the firewall and route it along the back side of the motor/firewall. Connect the vacuum hose the the larger port on the servo, connect the electrical connector, and connect the ground cable to that weird long connector coming from the passenger side engine wiring harness. You know the one everyone asks "what is this for" every few months. CONGRATULATIONS, now you belong to the club of knowing what that connector is for, and actually using it.

 

 

8) Install vacuum harness. 

 

The kit came pretty complete with the vacuum harness and the 4-port vacuum reservoir (football). As I sat there staring at the mess of vacuum lines I wondered if there was an easier way. My MJ has a 97 XJ Dana 30, AW4, and NP231, so no vacuum 4x4 system. Heater control valve, what's that? I rummaged through some parts and found a 2-port vacuum reservoir (baseball) that I figured would work better. 

 

 

Removed the rubber elbows from the old vacuum harness, and found some new plastic tubing that I cut and bent. I used a heat gun to bend the tubing. Connected the vacuum reservoir to the smaller port on the servo.

 

9) Finish installing wiring harness (interior side), brake switch, vacuum release/TCC switch w/ bracket, speedo sensor, and clutch switch.

 

The very end of the harness has a single wire plug (gray w/ black) that fits right into the IGN slot on the fuse block. There's a 4amp fuse along with this plug, make sure it's in good shape.

 

 

Now if your MJ is pretty stock, you can replace the stock brake switch with the cruise control version. The difference is the extra set of prongs for the CC wiring. If you're cheap you could just splice into the wiring on the existing brake switch.

 

If your truck doesn't already have the vacuum switch bracket installed, its easy installed with one self tapper. Then just shove the vacuum switch into the steel grommet in the bracket, and connect the vacuum switch with the TCC wiring that should be under the dash.

 

I have a 96 XJ brake booster. Normally this wouldn't be an issue if I had ground down the "flat spot" on the booster rod, but when I did the BB install I removed the stock brake switch and vacuum/TCC switch completely, replacing it with a GM brake/TCC switch (NAPA #SL186) instead. This decision created additional "challenges" when I did this cruise control install, one of which is what to do with the cruise control brake switch. Since I didn't want to mess with the brake booster rod, I decided to just tap into the wires going to the GM brake switch, forgoing the stock brake switch again.

 

 

The other challenge I ran into was mounting the vacuum release/TCC switch. My MJ already had the bracket installed, along with the vacuum/TCC switch. Presumable this is because my MJ is an auto, and needs a TCC (torque converter clutch) switch regardless of it if has cruise control or not. But when I did my BB install I ditched this switch and installed the GM switch in its place. So how was I going to mount the vacuum/TCC switch for the cruise set up? I certainly didn't want to take anything apart unless I had to...

 

So I decided to cut the switch bracket...

 

 

Then bolt this "plate" with the GM brake switch, leaving an extra hole for the vacuum switch.

 

 

 

Because my GM brake switch also acts as the TCC switch I did not hook anything up to the vacuum/TCC switch. So now it acts as a vacuum dump valve. If your set up was stock then you would plug the connector from your old switch into the new vacuum switch, if required.

 

Now plug in the connector from the speedo sensor.

 

 

If you have an auto then the clutch switch connector can be plugged into itself, and may already be. If you have a manual then this connector is installed on the clutch switch, which is installed on it's own bracket.

 

 

 

[Airborne Janitor]

10) Install cruise control module

 

This fun yellow box is installed on the lower dash trim with two machine screws. Install and plug in the long connector from the wiring harness.

 

 

11) Install turn signal lever/multifunction switch

 

Removing the old turn signal lever is as easy as just pulling it straight out of the steering column. You may have to wiggle it a little bit for removal.

 

Plug in your new turn signal lever to make sure it fits first! Route the cruise control cable down through the steering column (easier said than done). I ended up having to pull the steering wheel and getting under the turn signal switch to route the cable. You will need a steering wheel puller and a lock plate puller.

 

 

 

A thin piece of wire helps here, such as some welding wire. Loop one end of the wire around the CC connector and then fish down through the steering column. Plug it into the last connector on the wiring harness.

 

 

Now of course I had an issue with the supplied lever. It's almost like the "rod" is too long, so when installed there's a 1/4" gap between the "selector sleeve" and the rest of the lever.

 

 

The stalk still functions, so for now I will be using it for testing purposes. Will update when I find a suitable replacement.

[Airborne Janitor]

I just finished up the install and was able to take it for a test drive. 

 

Issues:

1) After wiring everything up and reconnecting the battery, I noticed my brake lights were on. Looking under the dash something smelled "hot" and I noticed the 4amp CC fuse had blown. FIXED - Figured out I had reversed the polarity of the CC brake switch wires when I tapped into the GM brake switch.

 

2) My wipers no longer work. I'm wondering if its a fuse or if I accidently disconnected the intermittent wiper module. Will look into it. FIXED - the connections on my wiper module came loose during install.

 

3) The cruise control functions! At speeds under 40MPH it works perfectly, engaging with the turn signal controls, and can be shut off with either the controls or the brakes. 

 

At highway speeds however it turns from cruise control to turbo control. Activating the cruise does lock the speed, but it also accelerates as well. So if you engage at 70MPH you will start to speed up to 75, 80, etc.

 

FIXED - Adjusted the potentiometers on the control module. See below.

 

4) The before mentioned issue of the turn signal lever being the incorrect length. FIXED - ground a 1/4" off the end of the rod and used an o-ring to close gap. See below.

 

Further troubleshooting required....

[fiatslug87]

Nice write-up, appreciate it!

subscribed

[Airborne Janitor]

Took a few measurements of my old turn signal stalk. Hoping to find a proper replacement. I guess Mopar part numbers are 56000034 & 56004595.

 

 

 

[Salvagedcircuit]

Excellent documentation! I don't think I've ever used cruise control on any vehicle, but dang if I ever wanted to add it to my comanche, your guide looks pretty complete.

I nuked my original '88 TCC switch and I forgot to rewire it into the 96 combo brake switch after I did the WJ booster+master swap. Really hoping it has not damaged something >.>

 

[Airborne Janitor]

I didn't have much look finding a replacement turn signal lever, even searching for GM originals on ebay. Tried modifying the included kit lever and got it to work. 

 

Ground 1/4" off the end of the rod.

 

 

There was still a small gap between the selector sleeve and wiper controls, so I used a 3/4" x 3/32" o-ring to close it up. 

 

 

 

Put a little grease on the o-ring to prevent squeaking.

 

 

[eaglescout526]

On 12/18/2022 at 2:46 AM, Airborne Janitor said:

At highway speeds however it turns from cruise control to turbo control. Activating the cruise does lock the speed, but it also accelerates as well. So if you engage at 70MPH you will start to speed up to 75, 80, etc

You’ll need to look at the FSM and dial in the potentiometers as specified. I factory rest all the modules so they operate at the minimum 30mph pulses. This practice just ensures the system works and engages. As far as setting it to lock on at the desired speed will require further dialing in of the pots. It’s one of those things where you can’t bolt in the regulator just yet until cruise has been finely tuned. It’s not the most fun part but it’s satisfying knowing you got your cruise dialed in. And also I send the regulators as factory reset because not all components may play nicely with the settings as I found the box IE ground could have resistance at the harness and can mess with the readings the regulator reads from the pulse generator. Fun stuff it is. Anywho this gets my seal of approval. Looks like my printed instructions were very comprehensive. 
 

 

I just remember. I keep this pic of the section that talks about the regulator in my phone. 
 

[pizzaman09]

Is there supposed to be a thread adapter between the speed sensor and the short cable?  The short cable I have ordered is identical to the one you have pictures, however the threaded connection on my speed sensor is the same diameter on both sides.  Your speed sensor seems to have a different thread on each side.  

[eaglescout526]

Yes there’s an adaptor. Chances are the adaptor is still in the parts rig you pulled CC from in the original adaptor. 

[pizzaman09]

1 hour ago, eaglescout526 said:

Yes there’s an adaptor. Chances are the adaptor is still in the parts rig you pulled CC from in the original adaptor. 

The adapter is probably in the cable of the jeep someone on ebay pulled it from.

 

I guess I fire up the lathe and sort it out.

[eaglescout526]

5 minutes ago, pizzaman09 said:

I guess I fire up the lathe and sort it out.

Make a metal one?! Well that would be pretty BA!

[87MJTIM]

Looks like this:

 

 

[pizzaman09]

It was good fun stacking some gears on the side of the old lathe and turning the piece.  For those interested, the hole is a standard 5/8-18 which fits on the speed sensor.  The outer thread is an oddball 7/8-18 which the speedo cables fits.  I made it exactly 3/8" long and skipped the drive slots.

[Airborne Janitor]

On 12/22/2022 at 5:56 PM, pizzaman09 said:

It was good fun stacking some gears on the side of the old lathe and turning the piece.  For those interested, the hole is a standard 5/8-18 which fits on the speed sensor.  The outer thread is an oddball 7/8-18 which the speedo cables fits.  I made it exactly 3/8" long and skipped the drive slots.

 

 

Nice work! Wish I had a lathe and mill in my shop!

[Airborne Janitor]

On 12/19/2022 at 9:30 PM, eaglescout526 said:

You’ll need to look at the FSM and dial in the potentiometers as specified. I factory rest all the modules so they operate at the minimum 30mph pulses. This practice just ensures the system works and engages. As far as setting it to lock on at the desired speed will require further dialing in of the pots. It’s one of those things where you can’t bolt in the regulator just yet until cruise has been finely tuned. It’s not the most fun part but it’s satisfying knowing you got your cruise dialed in. And also I send the regulators as factory reset because not all components may play nicely with the settings as I found the box IE ground could have resistance at the harness and can mess with the readings the regulator reads from the pulse generator. Fun stuff it is. Anywho this gets my seal of approval. Looks like my printed instructions were very comprehensive. 
 

 

I just remember. I keep this pic of the section that talks about the regulator in my phone. 
 

 

Pulled the control module and set the dials to exactly how they are pictured here.

 

Cruise works perfectly now! I tested it at 60, 65, and 70 MPH, checking speed with GPS in addition to the speedo. No more than +/- 1 MPH on the cruise speed when engaged. 

 

Thanks again @eaglescout526 for the kit and tips.

 

I added some additional pics and information to the write-up above as well.

[eaglescout526]

No Problem!

[pizzaman09]

Some additional cruise control pedal switch thoughts.  

 

This is how the clutch switch is oriented and installed.  The bracket was very difficult to tighten the bolt up on, a ratcheting 8mm box end wrench saved the day 

 

Additionally, I didn't acquire a factory brake light switch with the 4 spade terminal connections.  Instead I purchased doorman 85412 and split the outputs.  With a little Ox-Gard on all the fittings, it basically looks factory.  As a bonus I didn't have to swap out and  realign the switch!

 

 

[eaglescout526]

Huh. That’s one way to do the brake switch. A lot cheaper than a new switch. 

[saveevryjp1998]

On 12/22/2022 at 6:38 PM, pizzaman09 said:

The adapter is probably in the cable of the jeep someone on ebay pulled it from.

 

I guess I fire up the lathe and sort it out.

 

On 12/22/2022 at 6:44 PM, eaglescout526 said:

Make a metal one?! Well that would be pretty BA!

Any ideas why the factory used a plastic adapter there instead of metal to begin with? It wouldn't have something to do with a like a magnetic static charge or interference at the connection would it? It's strange why they simply didn't use the exact male/female threads otherwise after producing millions of them. It seams like an extra step and part on the assembly line. 

[eaglescout526]

24 minutes ago, saveevryjp1998 said:

Any ideas why the factory used a plastic adapter there instead of metal to begin with?

Actually if you look back at when the kit was first started by Dana, they had metal cased speed sensors where the threaded sides were different. Now as time went on and the kit was made on the side by Dana until someone bought it, they went to the plastic sensor which I’m sure accommodates for two different speedos, hence the adaptor. I don't know which make had the cable be the same on either side of the sensor but I’m willing to bet it was one of the big 3. 

[pizzaman09]

I'm willing to be it was just an economic decision, injection molded plastic is far less expensive than matched metal components.  You don't have to worry about corrosion, the plastic is kinda self locking.  With respect to the sizes, the large one is the standard thread size apparently for speedometer cable drives, the smaller connection allows for the cable to pass through a smaller hole in the firewall.