Junkyard Cruise from Scratch - Amplifier Mounting?

[lowspeedpursuit]

I don't know a ton about electronic logic, especially AC and converting between different types of signal. I wonder why the wiring diagrams break VSS ground out separately, then? I assumed they want a more direct path to avoid the potential for too much resistance along the common ground, but it could save trouble extending that PK/O wire if it isn't really necessary.

I think the VSS probably checks out at this point, although I still wish there was a way to test its output directly. 8000 p/mi should also be 8000 p/min @ 60mph, which gives 35/60*8000 = 4667 p/min @ 35mph. So, I feel like you should be able to divide that by 60 and measure 78Hz with a capable multimeter, but mine shows 1kHz, so I must be misunderstanding something.

Various parts will be here Wednesday. I grabbed a '94 Mustang module for $20, but I won't know if it's actually compatible inside until it gets here. Affordable green-box modules are basically hen's teeth around here at this point.
A way to test the modules would also be nice, but while I understand what they do, how exactly they work depends on the chip inside, which is kind of a black hole of information.

 

[RonD]

VSS ground wire(pink) usually is grounded in the cab where devices using it are located, vs frame or engine/trans ground
Technically all the grounds should be equal at all locations on a vehicle, real world.............usually not, lol


Useless extra info
For cruise, PPM needs to be present but not calibrated to speed
For electric speedometers, started in 1995, it did matter
The VSS signal from the trans/transfer cases were calibrated with rear axle ratio and tire size(rotations per mile), calibration was done by the changeable Driven gear on the VSS unit to calibrate MPH for speedo cable and VSS, cruise gets the same signal but has no idea what "speed" is, lol

In 1998 Ford high jacked rear axle ABS VSS and ran that 25,000ppm(approx.) signal to the GEM module which converted it to 8,000ppm using tire size only

In 2001 all transmissions(manual and auto) got an OSS(output shaft speed) sensor which was about 32,000ppm, it was connected directly to computer which had rear axle ratio and tire size
Compouter would then send out the converted 8,000ppm signal to speedometer and cruise
GEM and computer could be programmed for tire size changes and axle ratio changes as needed

In 2001 and up 4x4s, the computer would get the "heads up" when 4low was activated and it would change the ratio to make speedometer accurate in 4low

 

[lowspeedpursuit]

So, solution first: I had a bad connection where I tapped Brake On/Off (LG). That wire isn't open with the brakes released; it's grounded through another circuit, and cruise won't work without that ground. Service manual troubleshooting doesn't list that as something to check under "speed control does not work", but it's listed later under "speed will not set in system".

Since I have it, the '95 Mustang amp appears to work so far in spite of being a different board inside. I've mentioned the '93 Explorer uses F1VF-14A608-CD. The Mustang uses a redesigned F3ZF-14A608-AA:

You can see the same D9AF-14A607-A3B chip, and the other components all look basically the same as well, just moved around. I built a SPICE model of my original amp in case I had to screw around with it at some point, and I quickly verified a couple of circuits on the new amp before hooking it up. Among the pins on the IC, 1 and 24 are grounded, 13 is V+, 12 goes to Brake On/Off, 2 and 3 are jumped, and 6 is unused. The only obvious difference between the boards is that pin 1 on the big connector has reverted from an unused "cruise light" to a duplicate brake signal pin, just like it was on the older E3- and E7- boards.

In any event, it seems like there's greater amp availability than I was led to believe when I started gathering parts. It is kind of a moot point if you're grabbing everything from the same donor truck, since the servo is still pretty specific. My servo is out of a 4.0 truck with a rebuilt actuator cable, so I'll write that up at some point when I have the time.

 

[RobbieD]

Thank you for the update, and for the information. Great work!

 

[rumblecloud]

Bookmarked this thread...thanks.
I don't use cruise very often and my depth of knowledge about the system is so far below what this string is telling me ---
I've gone as far as replacing the amp several times from JY pickups (whenever I go, I just grab one if it's available).
But one day...I'll try to tackle it and this thread will be my go to.

Thanks
R

 

[lowspeedpursuit]

Cruise control is a game-changer, and I can't believe I've put up with not having it for 7 years now. Everything worked great on a real test drive, so I'll say the Mustang amp is definitely compatible.

Working on the "safety" systems, I got the Brake On-Off switch wiring finalized and routed through the clutch switch. My harness is missing the cruise pins there, and that pigtail is apparently $50 new. But, I'm already bypassing the clutch ignition interlock, so I just swapped those unused pins over to positions 3 & 4.


This leaves me with another request for better pictures: I'm trying to set up the dump valve. This is already kind of a shitshow because I've been using its hole in the firwall to run my own wires (A/C, heated seats, and now cruise), but more importantly, it mounts pretty far above the brake pedal. The first pic is the wrong truck, but it's clearer on how the valve clips in. From the same thread that showed me how the amp mounts, apparently there's this giant piece of plastic that clips to the brake pedal that I don't have:

The manual doesn't really show this part at all, and it's not considered part of the brake light switch or the pedal assembly, so I guess it's supposed to be part of the dump valve.
Has anyone got any other pictures of it, maybe even out of the truck, so I can fabricate one?

 

[RobbieD]

This leaves me with another request for better pictures: I'm trying to set up the dump valve.

See if these help. I'm not 100% sure on a '94 model; these are how it mounts in a 1990.

On this setup a metal clip holds the dump valve; it just pushes in from the top until the pedal bracket closes the valve.

You can also see the vac hose coming through the firewall in the first pic.

 

[lowspeedpursuit]

Sweet! Thank you. I think we do have the same pedal assembly, so I should be able to work something up from that.

The vac routing is interesting. I have an unused punchout in my insulation there, but I don't see a corresponding punchout in the firewall itself. I've got the vac line coming through with my wires a few inches straight down from yours, below C105.

 

[VICI]

If you need a verified working speed amp, got a stack from '93 and '94 explorers. 2nd pic in post #21 is of my '94 Ex from EF, working on getting that cruise engage light working.

 

[lowspeedpursuit]

Appreciate it. Looks like the source in post #11 upgraded their forum software and the link I used doesn't work, but IIRC the red Taurus box has the same form factor as ours and actually uses a cruise control light (random '91 schematic says "electronic cluster only", for what that's worth), if you want to crack one open and see how the pin is connected.

What are you using for the light itself?


EDIT: Realizing I never circled back to this thread at all. I attached the SPICE model I made of the green box. Again bear in mind I have no idea what I'm doing, there might be mistakes, and there's no way to get the Motorola chip except from an original box anyway.

 

[VICI]

Appreciate it. Looks like the source in post #11

the post #11 references the older speed amp, which is present on the 91&92 explorer and that board, while It fits doesn't have the circuitry for the light as far as I could tell. the later board has a connection and printing for it, but all the boards I found had the necessary components (diode D5, jumper JP2, resistors, transistor at Q5 and what I assume was just an lm358 at IC2) unpopulated. Never found a vehicle that actually had a cruise control active light to see what is actually intended to be there. guess I have a motive of curiosity to inspect a taurus.

Made that post about cruise control on EF when I was trying to get an indicator. Don't have it connected to a lamp, as the plan changed to use it as a signal to change a status graphic for JP tour vehicle electronic dash. That's hiatused atm though. sidenote another fordcentric forum I found useful is garysgaragemahal.

 

[lowspeedpursuit]

This should be the proper link to the other thread on garagemahal/bullnose forum I was thinking about. I was mistaken: they examine a red Taurus module, but they also say the donor Taurus lacked a cruise light, and the pin is disconnected. You can see JP2 is unpopulated in their photo.

They go on to suggest looking in comparable Lincolns. It looks like having the "electronic/digital cluster" may be the actual key here.

This is red, and kinda spendy. Dunno if it would necessarily be the right box with the indicator wiring without a way to confirm the cluster type in the donor car.

1990-1991 Lincoln Town Car Cruise Control Amplifier (F1VY9D843A) NOS | eBay

(F1VY9D843A) NOS. Old Car Clearance.

www.ebay.com

 

[lowspeedpursuit]

Okay, starting to make moves to add cruise to the new '95. Clocksprings F67Z-14A664-GB unique to '95-'97 are discontinued. I already ordered an ebay NOS unit, but for tech reference, has anyone compared the F67Z- clocksprings with the F87Z- which are still available?

The dashboards are basically the same, right? So is there any chance it's just wiring differences that can be easily corrected, or are they completely different parts?

I have another '95 non-cruise parts clockspring on the shelf somewhere I can grab a picture and measurements of, although I may already have cut one of the plugs off for another project.

 

[Terrys87]

I am slowly getting all the things I need for Cruise Control. I recently found a truck with the Dump Valve bracket in the yard and am going to go get it this week. Will follow along with this thread and add to it as well. Mine is for an 88 Ranger. I need to get a Master Cylinder that has the electrical plug on it.

 

[lowspeedpursuit]

Do you need a master cylinder switch in '88? That's two enthusiast generations away from '94, so I'm not an authority, but I don't see that in the '94 manual, and I don't see '88 brake masters broken out into cruise/non-cruise on rockauto.

My understanding is that '94-down vacuum-based cruise uses the dump valve, and '95+ fully-electronic cruise uses the master cylinder "brake pressure switch", which are functionally equivalent: an emergency cruise shutoff if the brake pedal "brake on-off" switch doesn't work to deactivate it.

Full disclosure: I never fabbed the bracket to make the dump valve work. Since the valve is normally open, and the bracket holds it closed, I have the vac line capped off and ziptied near the ebrake release. I figure in the unlikely event of a runaway cruise situation, I can just shift into neutral and let it bounce off the rev-limiter while I rip the cap off the line to dump vac.