I was able to get a few hours in the garage this weekend, so I pulled the car in and yanked out the console, instrument cluster and dash to do some work.


My ABS headliner from Fiero Store is also here, but I need all to pull all the rest of the trim panels out of storage before I mess with it. I did pick up some peal & seal to cover the top side with to help cut down on plastic squeaks. I am planning to install it w/o any foam/fabric and just the plastic textured surface.


First order of business, was the instrument cluster. The ground circuit is weak in the plastic circuit, so everything works until you turn on the back lighting, then you lose the tach and fuel level, and a couple other interesting things happen. All my spare clusters are buried in storage, so I figured I would run some additional ground wires soldered to the metal terminal plates to help support the ground load. Then these wires will be grounded to one of the bolts on the steering column.


I am working towards a cruise solution through 2 separate methods.

METHOD 1: a $350 module that plugs into the pedal, OBD2 port, and wire up 1 switched power wire. It intercepts the pedal voltage back to the ECM and adjusts the voltage signal to speed the car up/down. It gets the brake signal and VSS input through the OBD2 port (GM LAN) and includes the control knob for all the cruise function. Its super simple to hook up, but I am still in the debug process with the vendor. Per their troubleshooting manual, all 4 pedal wires at the controller should be 4V and mine are 2V and 5V. They normally use the TBSS pedal and it is one number different. With this module hooked up, the car immediately goes into limp mode and it kills function to the pedal. The vendor is debugging this on their end. I sent them resistance readings on my pedal at fully released and WOT and a copy of my tune so they could look for differences in it... If they don't get something figured out soon, I will likely return it.

METHOD 2. AR Digital cruise module like used is many 3800 swaps. The only signal it needs from the ECM is the 4000ppm and I am already using the 4000 ppm output from the E67 to drive my speedo (and the 88 Speedo has a 4000 PPM output too). The rest of the wiring is pretty basic, especially since it will be mounted in the passenger compartment. The AR cruise module uses a cable to pull the throttle blade open, but I don't have any throttle bracket on the TB (and the ecm probably wouldn't like seeing it move w/o matching movement from the pedal). So I want to use this cable to actuate the pedal for cruise. When the car needs to speed up, the pedal needs to be pressed, to slow down, it needs to be released.

So fab time...
My garage doesn't have a 220V outlet, plus my welder is at my brothers 45 miles away and I haven't got setup for welding gas bottle here... So I used a 10% off coupon and purchased a ProMig 140 from Lowes. It is the baby brother to my other welder (ProMig 175), but it will get the job done... even with flux core wire.


The cruise module pulls the cable to speed up, so I needed a bracket that would pull the pedal towards the floor. So I fabbed up an extension to the top of the pedal and a cable mounting bracket that comes off the stock 2 bolts for mounting the stock fiero gas pedal. There is slack built into the bracket as you can see here with the pedal fully released.




Here is a video of the motion of the cable as the pedal is cycled from fully released to WOT and back a few times.


Mounted in the car:


Routing of the cruise control cable:


General placement of the AR Cruise Module:


If I can find a shorter cable, I might try to mount it in the center console in front of the shifter:


The main concern I have about the AR Cruise Module method, and the reason the level arm is quite long is the gain... cable movement vs. delta in speed. It needs to barely move the pedal to get a response (2800 lb car, 90mm tb, and non-linear movement between pedal and throttle body). That is why I made a 2nd lower mounting hole if I need to speed it up. If need be, I can also re-calibrate the pedal % pressed to TB % open in the 70-80 MPH cruise range to help dial it in.

Not much is going to happen for the next few days. I will be traveling to NYC on Tues, returning on Wed. Next weekend I have a company picnic to attend, but may be able to get some stuff done.

[This message has been edited by fieroguru (edited 08-16-2015).]