clokker

iTrader: (2)

I just installed cruise control in my '91 NA...naturally, it doesn't work.
Sadly, this doesn't surprise me much.

Having read the FSM, I tried the "diagnostic mode" to see where I might start troubleshooting but it won't even enter this mode to spit out codes.

When the main button is pressed the "cruise" light comes on but nothing will entice it to begin diagnostics.

I've tried two switches and two control modules to no avail.

Any ideas would be appreciated.


Edit:
The "stop" and "meter" fuses are good (replaced them anyway) and I have a brand new stop switch with the cruise connection plugged in.

HAILERS

Where did you get the cruise control components from? What year car. What type car. Turbo/non turbo.

You can get codes for the cruise control on a series five. How 'bout that. Learn something new every day.

Jpk3200

May be unlikely that both switches are faulty, but have you tested the switch positions with an ohm meter? T-26 of FSM.

Maybe the unit isn't seeing the ground that RESUME should put out.

clokker

iTrader: (2)

Parts came from a '91 NA donor car in the classifieds (claimed to be working at the time of sale).
The second switch and computer came from the junkyard (an '89, IIRC).
Both switches and computers have matching part #'s.

Both switches pass the continuity tests.
I haven't tried the light bulb setup yet...don't have a bulb handy.

HAILERS

You could get a meter out. Pull the plug off the cruise control unit. Put one meter lead on a known ground point. Then,meter on ohms, one at a time, put the other meter lead on the L/W wire and go to Resume, then the meter lead on the L/R wire and go to Coast, then put the lead on the G/O wire and go to Set. Do those with the key OFF and in your pocket.

Each time you go to those switch settings, momentarily, the meter should show continuity. If they all do that, then that part of the switch is good.

Then, this time with key to On and the Main switch on the cruise switch engaged, look for batt voltage on the G/Y wire. It should be there.

Then check the G wire for batt voltage. None should be there. Push the brake pedal and power should now be there as long as the brake pedal is depressed.

Check the Y/L wire for voltage with key ON. None should be there. Step on the clutch and it should have batt voltage.

Check the B/Y wire for volgage with Key ON. Should be there.

You might check the parts fische to see if you have the right actuator in the engine bay. Also check the parts fische to see if you have the right cruise control unit part number for your car. Parts fische are in the FAQ. sorta.

Just do common sense wire checks like those above and you'll find your problem.

jackhild59

iTrader: (7)

Just a wild guess, but did you verify the clutch switch operation?

clokker

iTrader: (2)

Isn't that the same switch that allows the starter to function?

When I discovered that there was a special brake light switch needed it was easy to see the extra- previously unused- connector for the cruise circuit but I don't see anything like that for the clutch switch, so I assumed the switch I had did double duty.
I further assumed that if the switch allowed the starter to engage, it must be OK.

Lots of assumptions, I know.

Jpk3200

No. That would be the clutch interlock switch located on the far side of the driver's left foot.

The clutch (for cruise) switch he's talking about is located above the pedal like the brake switches.

A bad clutch (for cruise) switch could certainly prevent the system from working, however, it shouldn't prevent you from getting into the diagnostic mode. One of the features of the diagnostic mode (actually there are two modes to test) tests the condition of the cruise clutch switch. It spits out an error code if it isn't working.

clokker

iTrader: (2)

Damn...so there's another switch to find/install?
I'll have to get up under there again and see what's what.

HAILERS

.Get the meter out and follow the TS page attached any you can figure out your problem.

THAT ts page is with the connector on the cruise control unit. You'd backprobe the wires on the connector.

Is the vacuum line connected to the actuator? Or is yours an all electric actuator? That'd be a clue.

HAILERS

I was under the impression all cars had this clutch switch whether or not they have cruise or not. Might be wrong.

Seems to me the cruise will work with this switch in the backyard. I mean there is no continuity when the pedal is released. About the same thing as it not existing in the first place.

Jpk3200

^ you're right. I forgot the clutch switch worked opposite to the cruise brake switch.

HAILERS

I don''t have a series five car. I'm looking at the series five diagrams I attached above, and I can't help but think there's two BRAKE switches on a series five??????????

I say this for two reasons. There is a wire going to the cruise unit that says it's from the stop lights (G colored wire). It is one color. But if you look at the diagram you see a BRAKE SWITCH going from the cruise unit to the cruise actuator. It has different colored wires on it than the brake switch (L and LO colored wires).

It seems you'd need to have that switch shown on the diagram. The one with L and LO wires. It's called F-53 in the picture.

So........does the series five have TWO brake switches. Or maybe a brake switch with three/four wires on it? I can't figure this out and I looked at the BRAKE section which shows only one switch and seemingly only two wires.

I've no idea why I'm writing on this thread as I don't have a series five, but it's bugging me with the brake/stop switch.

My series four has the clutch and brake switches, and when depressed they send 12vdc to the cruise unit which in turn disables the cruise function. Series five input is a bit different evidently.

clokker

iTrader: (2)

It doesn't have two separate switches but there are two different switches that can be installed.
The non-cruise switch has just two terminals for the brake light and the cruise-specific switch adds two more terminals.

My actuator has the vac line and it's connected.

Today will be contortion day as I fold myself into the footwell and begin backprobing.
If I wasn't preparing for a three thousand mile road trip in a few weeks, I'd let this slide but 1000 miles on I-80 is a strong incentive.

Jpk3200

The brake switches on the S5 are in one unit, and there are two different connections on that unit as clokker said. One connection for the brake lights and one connection for the cruise system.

I think I said things wrong in a previous post. Yes, there is continuity for the clutch (for cruise) switch when you press in the clutch, and there is continuity for the brake (cruise) when you press the brakes. There is no continuity on the brake (stop lights) switch when you press the brake.

Let's say that you had neither a clutch (for cruise) switch nor a brake (for cruise) switch connected..... I would think that you would still be able to engage the cruise control, except that pressing the brake or clutch would not disengage the cruise. (And of course you would get at least two error codes when you run the diagnostic test).

Dunno, maybe those are needed to enter diagnostic mode, but I doubt it.

clokker

iTrader: (2)

Ok then.

I confirmed that I do have the clutch switch- which is odd since I didn't have the cruise brake switch (but do now)- and it is connected.

Managed to tweak about half the muscles in my ancient back as I contorted my way below the dash...hopefully, some aspirin and a day or two will fix that.
Probably going to remove the seat to free up some room when I go back under to backprobe things.

Oh joy.


Thanks for the help so far.

HAILERS

Remove the steering wheel.

misterstyx69

iTrader: (142)

Clokker..I installed Cruise on the 86,but never Installed that Relay under the Brakes.I only Noticed it along time after I had it working..I only had the Cruise CPU,the Switch,and the actuator assembly with cable to the Throttle body.I found that IF the Speedometer is not Working(not hooked up) it will not Work.(no signal to the Cruise Cpu from the speedometer Cluster).anyways,try with just those parts.

HAILERS

The JPK3200 got me looking at the series five manual and how to interrogate the thing. He made a good point about the gnd when you go to RESUME. Seems if that does not work, then the bit check isn't going to work.

Then I noticed at the bottom of that page where it says, if you don't exit the self diagnositic check, the cruis will not work. Unless you drive over sixteen mph. Maybe the speed signal is missing?? Like mentioned above by someone else? Sooooooooooo...you might, when all else fails, remove the battery cables for a minute or so and then reattach the battery and go for a ride???? And try, try, try again. It's a remote possibility.

clokker

iTrader: (2)

Speedo works fine.

I shall check for ground first thing.
Battery disconnect is easy enough, so that'll be second.

89fc3sT2

iTrader: (12)

I hope you get it workin son bro I do 44 miles everytime I have work on the highway n Im so happy I didnt remove that ****.


Trini

clokker

iTrader: (2)

OK, update time.

Trying to follow the diagnostic advice from Hailers (thanks, dude) and the FSM just about made my head explode...nothing was reading as it should.
I finally decided I'd reached the limits of my patience and expertise and took the car in to my friends at P.I.R....

...where it proceeded to make their heads explode.

Finally, after 2 hours of checking pinouts, reference voltages, etc., Mike realized that we were not seeing 12v at the computer module with the MAIN switch engaged but we DID see it with the switch OFF.
I'm sure he was almost embarrassed to ask- but he did- "Have you ever tried this with the MAIN switch off?".
"Why the hell would I even think to try THAT?", said I.

Awkward silence.
"But I will", I said.

On the highway, MAIN switch OFF, press SET and...nothing.
"Of course", I think, "Why in the world would that work?".

Resigned to failure (and a somewhat more uncomfortable trip to Chicago next week), I am randomly fiddling with the switch, toggle it down (COAST mode, theoretically) and the car begins to accelerate...I'm so amazed I nearly rear end the car ahead of me.

Much experimenting later, this is where it stands...
MAIN switch OFF, press SET, toggle down and increase speed a bit and the cruise works.
Toggle UP (supposedly to increase speed) does nothing.
Engage MAIN switch, again nothing happens...cruise mode continues.
Tap brakes and cruise disengages.

Drive back to the shop and explain what happens.
Much headscratching ensues.

We decide that since the cruise now works- in an admittedly bizarre fashion- just to leave it be for now.
The working theory is that either the computer or the switch, or possibly both, are from the wrong series RX...unfortunately, I have two of each but they are identical and we haven't any others to swap in to try.
Today I might try swapping out and trying every combination of switch/module- just to see what happens- but I have little expectation of success. I shudder to think what a new switch might cost- not that we're even sure that's the problem- and S5 used parts are thin on the ground out here.

Oh well, at least the cruise does work after a fashion, and that's better than when I started.

Jpk3200

Does your switch have a momentary or latching MAIN button? Should be momentary for S5. I've never attempted to install an S4 switch in an S5 cluster, but apparently you would know right away that the mounting places are a bit different.

What is the number printed on your control module? Is it something like X4T............? something. I think it was. FC01A?

HAILERS

The series four switch has a straight up and down face on it.

The series five SWITCH has a CANTED face on it.

At one time I used a series five switch on a series four car/control unit. I had to repin the plug to the switch plus I had to permanently depress the Main *button* for it to work. And work it did.

IN a earlier post I recommended looking at the output of the SET, RESMUE and other buttons at the Control Unit plug. On either series, when you push those buttons, you put a GROUND on their respective wires at the Control Unit. A momentary ground.

That's how I made a series five switch work on a series four. Found out which pins on the SWITCH were getting a ground when going to SET etc, and then rearranging the wires in the switch plug to match the signal.

Like the man said, I think you have the wrong switch for your car. Seems that way. IF I stll have that old series five switch I MIGHT post a jpg later today of the two together.

One question. When you MADE it work, did the car keep the speed you selected or keep on accelerating?

EDIT: Look where the red line is in the attached jpg. That is the area that is CANTED or not canted. That series five switch had been in a fire. The tiewrap stuck in the switch was to make it *make* all the time. High tech.

clokker

iTrader: (2)

My switch has the rounded (at least, not flat) face...it flows with the bezel.
The module's label reads:
FC01A
X4T35471
0725

The car holds the set speed.
Toggling down will raise the speed incrementally, releasing the lever it will hold the new speed.

It's hard to tell whether my MAIN switch is momentary or latching.
There is not a lot of throw and without looking at the CRUISE light I can't tell by feel if it's depressed or not. Both switches are like this.

Edit: I've considered playing with the pin out of the switch connector but am hesitant to do so.
Prior to this installation the gauge cluster had the blank off plate where the cruise switch would go and did not have the cruise brake light switch...so all indications would be that the car has never had cruise installed...how could the wiring be jacked then?