How to add cruise control to an Ls Fc and use the stock Mazda cruise switch

[willcoop]

After a 4 hour trip in my fixed back seat to and from a track day I really wanted to install cruise control into my Fc. I have seen threads and posts on different forums about using a common GM cruise control box for LS swaps. From what I read most GM vehicle after 1994 including S10s equipped with 4.3L engines came with the cruise control unit.

My local Pick n pull was having a 50% off sale during Labor Day weekend. I figured that would be the best time to try to get a cruise control unit out of a GM vehicle if I was going to add cruise control to my Fc. I was able to find a 1999 Chevy S10 blazer that had the cruise control unit.


(Make sure pin H is Blank)


Now that I had the cruise control unit I spent some time looking at the mazda service manuals for the wiring diagrams of the factory cruise control and switch. I able to find the pinout for the switch and wire colors. I verified these with my 1988 FC SE, there may be variation between the models and between S4/S5.


IND - INDICATOR LIGHT
ME - MAIN GROUD (ON/OFF)
MB - MAIN POWER
SE - SET
RE - RESUME
CO - COAST
E - GROUND
IL – ILLUMINATION


The Fc switch is wired opposite of how the GM cruise control switch would have been wired so relays are needed to get the Fc switch to work. I found a relay diagram that someone on 67-72chevytrucks.com created for a switch they were using. I tried wiring my relays the way that they did but realized the Fc switch was different. I was able to get the relays to work and modified the original diagram for the Fc switch.



Here is how to verify that the relays are working correctly and the switch will control the cruise unit.

Step 1

Wire up the relays as shown in the attached wiring diagram but don’t connect the wires to the TAC module.

Step 2
Test your initial relay wiring with your test light. You will probably have to have your ignition switch on in order to power the cruise circuit.
You want to verify that the brown/pink wire has power when you turn the switch to “on”
Next, verify the red wire of connector 1 is hot when you push the “set/cruise” button on the end of the handle.
Finally, verify the red wire of connector two is hot when you slide the slider on the handle to “resume/accelerate”.
If these don’t check out, check your wiring and connections.

Step 3: Connect wires to TAC module
Connect the Green/Yellow(ME) wire to pin A of the TAC module (Grey wire)
Connect the red wire of connector 1(Pin 30) to pin B of the TAC module (Dark Blue wire)
Connect the red wire of connector 2(Pin 30) to pin C of the TAC module (Grey/Black wire)


Step 4: Test it out on the road
Pretty much take out the vehicle and make sure all of the functions work. I suggest you take some tools with you and have your hand ready to turn off the ignition if something doesn’t work right as if you have not wired it up correctly there is a possibility of the cruise staying on and not being able to stop. If this happens, don’t panic, turn off your vehicle and pull over and figure out what you did wrong. Hopefully since we tested things in step 2 you won’t have a problem.






The GM cruise control unit has one wire for both Set/Coast and a wire for Resume/Accel. The Fc switch only has Set, Resume and Coast. There is no setting for Accel. I only hooked up the Set and Resume wired to my GM cruise unit. I have not tried it yet but I think that if I want to coast I will just have to hold down my Set button and if I want to accelerate I can hold down Resume. I may wire the Fc Coast wire into the same wire that Set is tied to if holding Set down does initiate coast but for now I am just happy to have cruise control.
If your Fc came with cruise control you will already have a cruise control brake switch and clutch pedal switch. I chose to only use the brake pedal switch to disengage my cruise control and did not use the clutch switch.

(Taken from Ls1tech and added Fc wire colors)
Cruise Module
A ........ Cruise "ON/OFF" input from switch  - Green/Yellow (Tap into at switch)
B ........ Set/Coast input from switch– Green/Blue or Blue/Red (Spare Blue/Red under steering column)
C ........ Resume/Accel input from switch– Blue/White (At switch)
D ........ Normally Hot 12v from brake/clutch switch– Yellow (At Fc cruise control box in driver side kick panel near fuse box)
E ........ Ground
F ........ Hot in run 12v - Blue/Yellow
G ........ Normally 0v brake input (needs 12v from brake applied only!) – White/Green (At Fc cruise control box in driver side kick panel near fuse box)
H ........ Should be blank on connector
J ......... Cruise engaged status to pcm (not needed!)
K ........ VSS from pcm/feed to cluster– VSS SIGNAL FROM INTEGRA SPEEDO or Pin 50 of red connector on PCM.



right from the GM service manual.......

"Battery voltage is applied to terminal F of the cruise control module when the ignition switch is in the RUN position. When the slider switch is moved to the ON position, battery voltage is applied to terminal A of the cruise control module. The cruise control module needs to receive brake input voltage at one of the following terminals once each ignition cycle before allowing cruise to operate:
Terminal D
Terminal G
The brake input voltage is received at the cruise control module through the following components:

The A/C CRUISE Fuse 12
The cruise control release brake switch
The cruise control clutch switch on vehicles equipped with a manual transmission
The voltage to the cruise control module terminal D is interrupted if either of the above switches is open. Terminal G must see a ground path through the CHMSL bulb in order for the cruise to operate properly. If the brake pedal is depressed, battery voltage is present at the module terminal G. When the slider switch is moved to the RESUME/ACCEL position, battery voltage is applied to terminal C of the module. With the set switch depressed, battery voltage is present at cruise module terminal B. Cruise module connector terminal K is the speed signal terminal. During operation the voltage will oscillate between the following levels:

A high of 4 to 5 volts
A low of near ground
The cruise module ground is at module terminal E."


Here are pictures of the cruise control installed in my Fc.

[digitalsolo]

STICKY!

[theantirotor]

I was recently going through the cruise system in my 94 caprice trying to diagnose an issue and came up with something that may apply here.  GM cruise does have a "cancel" function that deactivates cruise but keeps the set speed. It is accomplished by pushing down the set button and resume button at the same time.

Maybe you can rig the coast button to feed both the set and resume terminals proper signals. That might require diodes or something? I don't know.

PS I was able to get that same cruise control box at a local junkyard here for 14 dollars. So that is a good low cost option!

[Cman]

Good work. When I put the AC in trying to work this out with the two relays made me brain hurt so I used a separate switch with no extra relays. Besides it was hot.

Steve

[willcoop]

I was recently going through the cruise system in my 94 caprice trying to diagnose an issue and came up with something that may apply here.  GM cruise does have a "cancel" function that deactivates cruise but keeps the set speed. It is accomplished by pushing down the set button and resume button at the same time.

Maybe you can rig the coast button to feed both the set and resume terminals proper signals. That might require diodes or something? I don't know.

PS I was able to get that same cruise control box at a local junkyard here for 14 dollars. So that is a good low cost option!

I paid $17 for the cruise uni, it is a great inexpensive option.

I have been driving the car more and have done more testing on what the buttons do. If I hold SET down it enables COAST. If I press RESUME while cruise is on it accelerates. If someone wanted to make cruise work on the stoock switch they would just have to wire that into the same wire that SET goes to on the GM unit.

I have not tried pushing set and cruise at the same time to act as "cancel" but that would be nice to have.

[cholmes]

I'd like to add cruise, but the pics showing your install don't show up. Can you reload, or tell me where to find them? Thanks!

[Exidous]

I have the unit and connector if you need. Going to DBW and don't need it anymore.

[cholmes]

I appreciate the offer, I've got the unit and connector. I've looked at the Chevy and FC wiring diagrams, and have pretty much figured out the wiring.

I was asking about the original pics because more info is always better.

[money_pit_RX7]

I have the unit and connector if you need. Going to DBW and don't need it anymore.

How did you go about wiring up the DBW? My build has a 2010 camaro DBW unit and trying to get it to work with the stock cruise switch. My understanding is I would need something like the Digital Dakota CRC-2000 and some sort of "black box" to get the switch to run the needed inputs to the Digital Dakota.