Close



Page 1 of 2 12 LastLast
Results 1 to 25 of 29
  1. #1

    Default Common Problems With Cruise Control?

    Any common problems with Ford cruise I should know about? Mine is not working. It's 1990 model year, but it looks to me to be the same sort of thing a 4-Eye would use. Vacuum diaphragm and all that.

    My original thought was that it had something to do with my work on the car causing a connector to come unplugged or something like that, but now I'm starting to lean towards it being a normal failure. Connectors are plugged in, fuses are good, and module has power and ground in the correct places. And the vacuum lines are installed.

    Any thoughts? Thanks in advance!
    Brad

    '79 Mercury Zephyr ES 5.0L GT40 EFI, T-5
    '17 Ford Focus ST
    '14 Ford Fusion SE Manual

  2. #2
    FEP Senior Member Greywolf's Avatar
    Join Date
    Jul 2007
    Location
    Richmond, ME
    Posts
    967

    Default

    I'm not sure on a 1990, so this is sort of generic Ford testing. Mainly I'm unsure which years had the vacuum lines to the pedals for the dump valve, and whether any of the Fox Mustangs had an electronic speedometer.

    Check the "cancel" wiring at the brake (and clutch) pedals first; there's also usually a vacuum dump valve attached to one or both pedals to make sure the vacuum diaphragm releases. If these aren't connected, are shorted out, or the vacuum lines are leaking, the system will never be able to engage.

    If you have a vacuum pump, see if the vacuum diaphragm pulls in smoothly under vacuum and stays put; do this directly from the back of the vacuum diaphragm. Then move back to the intake manifold or canister line that feeds the diaphragm--if the car has the dump valves at the pedals, there will be a "T" somewhere in there. Repeat the test; if the diaphragm doesn't move (or releases as soon as you stop pumping) then you need to follow the vacuum hoses.

    Ford very nicely used an extremely similar arrangement of wiring from the mid-70s until the mid-90s for cruise setups; I don't have my notes on me but any Mustang wiring diagram from 1979 to 1993 (probably to 2004, but I can't say for sure until I get home in November) will have the switch data, as follows:

    In order to make wiring the steering wheel switches easier, Ford used only 2 wires to the cruise control buttons. Instead of an on-off switch, each switch is attached to a resistor, with a different resistance value for each function (on/off/set/accel/coast/resume; not all units have all those switches).
    In order to prevent weird problems, the resistors are such that no 2 or 3 buttons pushed in at the same time will add up to another resistor's value.
    On the cruise control module (varies per car), disconnect the connector, find the wire from the steering wheel (sorry, you'll need a wiring diagram for this, not sure if wire colors changed over the years; dealer installed cruise controls have the wire connections and colors marked on the box, and the "add-on" stalk buttons for the cruise use the SAME resistance values as the factory wheel buttons) and, with the car turned off, measure the resistance from the wire to ground as you press each switch, and compare it to the drawing (mostly making sure "ON" works, "OFF" isn't stuck, etc).

    Lastly, make sure the vehicle speed sensor is working. The VSS for most of these cars comes off the speedometer cable at the transmission, costs in the realm of under 20 bucks, and is pretty reliable. If your car doesn't have a speedometer cable (electronic speedometer), and the speedometer works, the VSS works. If it has a speedometer cable you'll have to test the sensor and wiring; I usually use a drill, an assistant, and a voltmeter. Hook the meter up between the VSS signal at the cruise module and ground; key on, engine off. Disconnect the speedometer cable at the transmission, carefully unclip the speedometer cable drive gear, and hook the drill to the tip of the VSS (keeps the drive gear from getting chewed up by the drill chuck). Have the assistant slowly ramp up the speed on the drill. You should see the voltage change with the speed of the drill. Try not to spin the drill at full speed, a few hundred RPM is plenty--you only need to see about 30mph on the speedometer to see a few volts. Technically you should be measuring pulses from the sensor to the cruise module, but unless you have an oscilloscope or frequency counter handy, the DC voltage your meter reads will tell you if the thing is working at all.

    I hope that wasn't too confusing.

  3. #3

    Default

    There is usually a horn ring rather then a more modern clock spring like newer cars. Basically there is a giant wiper in a circle around the steering wheel. Then there are wipers. Usually if a car sits for a long time, or thw plastic that holds it all together fails, you will have no cruise control (and offer horn).

    I can get mine to engage by pushing hard against the steering wheel. Same goes for the horn.
    2 1986 cougars (both 4 eyed and 5.0)
    1 1987 cougar

  4. #4

    Default

    Thanks!

    It does have the dump valve at the brake pedal, the speedometer is cable, but there is an electrical connection there too, and my horn does work. Also, I have an EVTM, so I should be good on what wires do what, but it doesn't have resistance values. I can certainly check and see if they are doing anything though.
    Brad

    '79 Mercury Zephyr ES 5.0L GT40 EFI, T-5
    '17 Ford Focus ST
    '14 Ford Fusion SE Manual

  5. #5

  6. #6
    FEP Senior Member Greywolf's Avatar
    Join Date
    Jul 2007
    Location
    Richmond, ME
    Posts
    967

    Default

    From the interwebs, I get these, which sound right (although I've done all this off the top of my head so far, so verify anything that doesn't make sense...):

    Resume, 2200 ohms
    Coast, 120 ohms
    Set/Accel, 680 ohms

    On comes from the horn relay, so it's whatever the resistance of the relay coil is.

    Off is direct to ground.

    Here's a dealer-aftermarket box illustration with wire colors, they *should* be the same for various years of factory wiring:

    http://www.thorssell.net/hbook/ccwire.html

  7. #7

    Default

    We used to replace a lot of the Servos back in the day, about 10 servos to 1 amplifier or speed pick up.

  8. #8

    Default

    Cool, these tests should be interesting to run. Thank you!

    My servo definitely looks like it's seen better days. I think it sat exposed to the elements for a while before I bought the parts car. I'm going to fight the urge to throw parts at it though.
    Brad

    '79 Mercury Zephyr ES 5.0L GT40 EFI, T-5
    '17 Ford Focus ST
    '14 Ford Fusion SE Manual

  9. #9

    Default

    Tried doing the vacuum test, but got confused. First, I tried pulling a vacuum at the port from manifold vacuum that comes from the vacuum tree. Is that the back? Anyway, it would not pull a vacuum there at all. I noticed though there's a line that bypasses the diaphragm that goes to a splitter where the line from the dump valve also comes in. It would seem to me THAT is actually the back, but is there a check valve or something in that splitter that vents the vacuum on the diaphragm? If so, how do you test vacuum there without running into a valve? Do I need to pinch something off to do a proper test? Neither of those ports would hold vacuum either though.

    Sent from my XT1650 using Tapatalk
    Brad

    '79 Mercury Zephyr ES 5.0L GT40 EFI, T-5
    '17 Ford Focus ST
    '14 Ford Fusion SE Manual

  10. #10
    FEP Super Member erratic50's Avatar
    Join Date
    Dec 2016
    Location
    Nebraska
    Posts
    4,575

    Default

    Cruise buttons work exactly like radio buttons on newer cars.... fun. If you don’t want cruise you can push a button to answer your phone with a simple adapter... lol

  11. #11

    Default

    I DO want cruise. That's why I'm trying to fix it.

    Sent from my XT1650 using Tapatalk
    Brad

    '79 Mercury Zephyr ES 5.0L GT40 EFI, T-5
    '17 Ford Focus ST
    '14 Ford Fusion SE Manual

  12. #12
    FEP Super Member erratic50's Avatar
    Join Date
    Dec 2016
    Location
    Nebraska
    Posts
    4,575

    Default

    Quote Originally Posted by ZephyrEFI View Post
    I DO want cruise. That's why I'm trying to fix it.

    Sent from my XT1650 using Tapatalk
    Understood. Just an observation. Carry on.
    -- James

    Favorite thing I’ve said that’s been requoted: “"40 year old beercan on wheels with too much motor"

    My four eyed foxes:
    "Trigger" - 86 Mustang GT - Black with red interior. 5.0 T5 built as Z. Original motor ~1/2 million miles. 18 yr daily, 10 a toy
    "Silver" - 85 Mustang Saleen 1985-006? (Lol) Rare 1E silver GT / charcoal interior. The car is a little bit of a mystery. Current project bought as a roller, tons of Saleen / Racecraft pedigree

    Also in the stable - my son’s car. 1986 Mustang GT Convertible. Black/Black/Black conversion. 93 leather. VM1 ECU. T5Z

    past foxes -
    1989 Mustang LX Sport 5.0 AOD white/tan black top. Once I ran this one down I caught a wife.
    Wife also had a 1987 Thunderbird Turbo Coupe in the 90's.

    I'm a four eyed pride supporter, are you? Become one today!
    http://vb.foureyedpride.com/payments.php

  13. #13

    Default

    I am planning on getting a new deck soon that will have that capability. It would be another cool modern feature to add to an old car. Totally my bag. Alas, no extra buttons though.

    Sent from my XT1650 using Tapatalk
    Brad

    '79 Mercury Zephyr ES 5.0L GT40 EFI, T-5
    '17 Ford Focus ST
    '14 Ford Fusion SE Manual

  14. #14

    Default

    I've only had a few issues with this version of cruise since the mid eighties. Right now I have an '84 with working cruise and a '92 with working cruise. I have never had the vacuum can die or anything technically fail like some electronic module. The first thing I want to ask is "Did this ever work?" Because if the answer is no, then I'd look more at something that isn't hooked up or moved over. It almost reads like you swapped this off another car? Is that true?

    If not, here are the issues I have experienced:
    One was the plastic clip that holds the cruise cable to the carb throttle cable got dried out because it was 30 year old plastic and it just crumbled apart and was no longer attached. The second one was an adjustment to that vacuum plunger on the brake pedal. The whole sensor is threaded so the whole thing is a giant adjustment. The other one was actually caused by the tilt wheel. We used to raise and lower the tilt every time we got in and out. Over time, the wiring that passes through there got stiff and brittle and eventually broke from all the flexing. I had to solder on a new piece of wiring right behind the tilt mechanism and that resolved it. Of course, a '90 does not have tilt as we all know. So...maybe at least just check the wiring going down the column to make sure nothing got dried and broken.
    Last edited by homer302; 10-04-2018 at 05:15 PM.

  15. #15

    Default

    Quote Originally Posted by homer302 View Post
    I've only had a few issues with this version of cruise since the mid eighties. Right now I have an '84 with working cruise and a '92 with working cruise. I have never had the vacuum can die or anything technically fail like some electronic module. The first thing I want to ask is "Did this ever work?" Because if the answer is no, then I'd look more at something that isn't hooked up or moved over. It almost reads like you swapped this off another car? Is that true?

    If not, here are the issues I have experienced:
    One was the plastic clip that holds the cruise cable to the carb throttle cable got dried out because it was 30 year old plastic and it just crumbled apart and was no longer attached. The second one was an adjustment to that vacuum plunger on the brake pedal. The whole sensor is threaded so the whole thing is a giant adjustment. The other one was actually caused by the tilt wheel. We used to raise and lower the tilt every time we got in and out. Over time, the wiring that passes through there got stiff and brittle and eventually broke from all the flexing. I had to solder on a new piece of wiring right behind the tilt mechanism and that resolved it. Of course, a '90 does not have tilt as we all know. So...maybe at least just check the wiring going down the column to make sure nothing got dried and broken.
    Thanks! Yes, the cruise setup got swapped from the 1990 LX 5.0 when I swapped over the drivetrain (SEFI), wire harness, and dash. Yes, it did work at one time. Later, I swapped from an AOD to a T-5, and I'm almost certain it worked at one point after that swap. I remember noting it somehow knew to disengage when I pushed the clutch in even though I hadn't yet wired a clutch switch directly to the cruise module.

    Speaking of which, am i the only one that finds it confusing the cruise clutch switch lets the cruise module know the clutch is in by OPENING? The
    brake switch is in line first, and if that isn't closed as if the brake pedal has been pressed, there won't be any current in that circuit anyway. Not only that,
    if the clutch switch is opened, the module is not going to see the signal from the brake switch!



    ANYWAY, I was thinking of wiring that switch in, but got all confused by this. My cruise hasn't worked in a few years. The connection to the throttle body on the SEFI engine is a pretty stout thingy that clips on top of the throttle cable connection point. The column wiring is certainly worth a look though!


    Alright so, back to the vacuum business. I thought I would ask in case anyone happened to know, but moved on and did some experimenting today. Everywhere I've googled "how to vacuum test Ford cruise servo" makes no mention of the bypass line and splitter I talked about above. Here's what they look like.



    The open port is where the line from the dump valve comes in. I tested that line, and it holds vacuum nicely with the brake pedal unpushed. So one thing eliminated. When I tested the servo for vacuum I got nothing. BUT, when I pinch off the bypass line, it at least pulls the cable linkage back and holds vacuum for less than a minute. This is what I believe to be the BACK of the diaphragm.



    According to what I've read online, that indicates a bad servo. But again, with no mention of the bypass or needing to pinch it off, I don't know if that's true or not.

    I went to try to remove the servo from the car so I could play with it on the bench. Turned out, that wasn't going to happen. I removed this front panel to try and get to a connector so I could disconnect the wiring. There is no such connector. The stupid thing is HARD WIRED to the car.



    I'm GUESSING I may still have a bad servo on my hands. Considering the fact that when I tried to pull a vacuum at the feed line from the manifold in FRONT of the diaphragm, I got nothing. The bypass wasn't pinched off, but I don't think that's a problem because the line to the dump valve was installed. I BELIEVE I still should have had a vacuum seal. But I most definitely did not.

    Electrical tests still to come...
    Brad

    '79 Mercury Zephyr ES 5.0L GT40 EFI, T-5
    '17 Ford Focus ST
    '14 Ford Fusion SE Manual

  16. #16

    Default

    Well, the servo tests out fine on the electrical side, and so do the switches. The wiring going to the switches actually looks really good. Nice, supple insulation and easy to move around. The OFF function does connect to ground, although the resistance is kind of high. I don't know if that's a problem or not. All the control values like RESUME and stuff tested out good.

    We're going to try a new servo. They are not available through normal channels, so I rolled the dice and went with a "new out of box" one from ebay.
    Brad

    '79 Mercury Zephyr ES 5.0L GT40 EFI, T-5
    '17 Ford Focus ST
    '14 Ford Fusion SE Manual

  17. #17

    Default

    Aren't old cars fun? I am seriously interested in what the final resolution ends up being. I know you will get there. I really, SERIOUSLY dig that it bugs you it doesn't work. It would me too!

  18. #18

    Default

    Quote Originally Posted by homer302 View Post
    Aren't old cars fun? I am seriously interested in what the final resolution ends up being. I know you will get there. I really, SERIOUSLY dig that it bugs you it doesn't work. It would me too!
    Oh yeah. plenty more old things on the car to break still too. I have a few connectors spread throughout the car that aren't plugged into anything. THAT bugs me too. Some of it, I can tell is from the airbag system, other things I have no idea!
    Brad

    '79 Mercury Zephyr ES 5.0L GT40 EFI, T-5
    '17 Ford Focus ST
    '14 Ford Fusion SE Manual

  19. #19

  20. #20
    FEP Senior Member Greywolf's Avatar
    Join Date
    Jul 2007
    Location
    Richmond, ME
    Posts
    967

    Default

    One other thought. In the mid-late 90s, Ford switched from the vacuum servo to a stepper motor design to pull the throttle cable.
    The wiring is the same for all the control parts, again, at least through the years of the SN95 Mustangs.
    I wonder if it would be possible to replace the vacuum diaphragm with the stepper motor arrangement?

    Sorry I haven't been on much, work is busy, ship is preparing for tropical storm and I'm working 12 hour shifts with the flu, so reading/writing on 4EP is low on the list this week.

  21. #21

    Default

    I've wondered that too. I know with mine I'd have to wait a while for the vacuum to come on and engage to hold my speed (maybe that was a bad sign, I don't know ). I like how on my newer cars it's instant. Having said that, I would rather experiment on a WORKING system than a broken one. We'll fix it first, then go from there. Plus, I already ordered the vacuum servo.

    No problem, you've been an enormous help!
    Brad

    '79 Mercury Zephyr ES 5.0L GT40 EFI, T-5
    '17 Ford Focus ST
    '14 Ford Fusion SE Manual

  22. #22

    Default

    The “new” cruise servo is installed and the car buttoned back up for a test drive today. Status: FAIL. I'm not sure where to go with it from here because the system passed all those tests I did! The “new” servo I got MIGHT be bad since I couldn't get one through the normal parts store channels. It was one that sat unboxed with a pile of other random car parts. I tried vacuum testing it, and the vacuum does bleed down, just not as fast as the old one. Is that bad? I don't know!

    I wish there was an indicator light that would tell me if the system becomes active when I push the ON button. As it stands, I have no idea if it's powered up, and just not able to actuate, or what the deal is. I'm 0% of the way closer to understanding what's wrong with it.

    I'm trying to think about it in terms of what other work I've done around the car where I might have disturbed something to now make the cruise not work. I'm not sure if it started after I had the steering wheel off in the past few years. Maybe. I'm just not sure. But I can't see it being the slip ring thingy though because the horn works great!

    I'm KIND OF happy to have the new servo now though because the wiring on my old one was very stiff and probably starting to get brittle. I'm not so sure that's worth the hundo bucks I spend on it though.
    Brad

    '79 Mercury Zephyr ES 5.0L GT40 EFI, T-5
    '17 Ford Focus ST
    '14 Ford Fusion SE Manual

  23. #23

    Default

    I suppose by process of elimination, you could say since we've eliminated the peripheral components and the servo, that leaves the amplifier/module as the culprit. I guess we'll try that. I found an NOS one on ebay. Keep your fingers crossed.
    Brad

    '79 Mercury Zephyr ES 5.0L GT40 EFI, T-5
    '17 Ford Focus ST
    '14 Ford Fusion SE Manual

  24. #24

    Default

    Alright, I installed the new module and that did not fix the problem. So, I re-ran all the tests. Here are the results just for fun.

    Servo tests:
    Orange/Yellow to Grey/Black -- 54.2 ohms.

    Orange/Yellow to White/Pink -- 119.8 ohms

    Purple/L. Blue to Yellow/Red -- 21.28 killi-ohms

    Purple/L. Blue t0 Brown/L. Green -- 42.9 killi-ohms

    Module Tests:

    White/Purple to Ground -- battery voltage

    ON Test:
    L. Blue/Black to ground -- Batt voltage w/ ON pressed , 7.75 Volts w/o

    Brake Circuit Test:
    Red/L. Green to ground -- 2.312 killi-ohms

    Horn Relay Test:
    -- skipped: horn works, and not an Escort or Tempo.

    OFF Test:
    L. Blue/Black to ground -- voltage drops to 0 with OFF pressed

    SET/ACCEL Test:
    L. Blue/Black to ground -- 4.37 volts with SET/ACCEL pressed

    COAST Test:
    L. Blue/Black to ground -- 1.46 volts

    RESUME Test:
    L. Blue/Black to ground -- 6.25 volts

    Some of the voltages might look a bit low, but this is a car that sits a lot and the temps are starting to get cold here in MN. Anyway take a look at that resistance on the brake light circuit! I did notice that last time, obviously but didn't know what to make of it. BUT, #3 of the brake circuit test states: "If the resistance is greater that 5 ohms, check for burnt out stop lamps... ". A few years ago, I installed all LED lights on the car. I thought I'd bypassed any potential issues, by using a no-load flasher and LED bulbs in the instrument cluster, but I'll bet that's what's causing my cruise not to work! I had no idea it would be sensitive to that! Looks like I need to get myself a resistor to put inline after all.
    Brad

    '79 Mercury Zephyr ES 5.0L GT40 EFI, T-5
    '17 Ford Focus ST
    '14 Ford Fusion SE Manual

  25. #25
    FEP Super Member erratic50's Avatar
    Join Date
    Dec 2016
    Location
    Nebraska
    Posts
    4,575

    Default

    Strange.....

    We have LED tail lights in my son's convertible and the cruise still works on it.

Page 1 of 2 12 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •