Audiovox CCS-100 cruise control replacement (can't do FE tests)
 

I won't do fuel economy testing without cruise control... and my aftermarket unit (Audiovox CCS-100) has quit working.

It's actually been out of service for a while. But I haven't been eager to do any speed controlled tests until recently, so I haven't looked into it until tonight.

I verified the wiring is all still good, and the red LED on the servo unit comes on when the set/resume buttons or brake pedal is pressed (as described in the first paragraph of the ROAD TESTING section on page 10 of the manual here: http://www.gadgetjq.com/av_manual.pdf ).

But it simply won't engage.

I also double checked that the vacuum line to the unit isn't kinked (it's not).

Any suggestions on what I should look at?

Maybe check and see if the diaphragm in the unit is holding vacuum? Remove the vacuum line. With the engine off, try moving the throttle by hand to move the diaphragm in the cruise unit, then put your finger over the vacuum port and let go of the throttle and see if it holds or not.

I hope you can get it working again. But if you end up ditching it, could I have the control pod for a small sum plus shipping? Ive been wanting one for a long time for the Celebrity as a nice looking replacement for the troublesome stock cruise stick but Audiovox wont sell me one by itself. Itd match my dash perfectly.

I have an after market cruise control that quit working and it turned out that it had a transistor burned out that activates one of the vacuum motors. I replaced that transistor and it is still working ten years later.

What I had to do to trouble shoot the device was to put it on the bench and devise a speed pulse signal, similar to the one produced by the car, with a signal generator. This allowed me to activate the unit and then examine what functioned and what did not. As soon as I could see that the throttle ON vacuum motor received no electrical signal to its terminals it was fairly easy to trace the circuit to find the burnt out transistor.

If you are not able to do a bench test of the unit, another worthwhile thing I have found to do, regarding malfunctioning electronics, is to visually examine the circuit board very carefully, and with a magnifying glass. Way more often than you would guess the culprit will turn out to be a cracked solder joint. This recently turned out to be the case with the windshield wiper control module of my GMC. It had 5 cracked solder joints on the plug connector. If you take the vehicle to a dealer to get the module repaired (very common problem on this model GMC) it costs about $240 as they just replace the module. Or you can discover the cracked solder and repair it yourself for $0.

I have found cracked solder joints to be the cause of the malfunction on a lot of electronic devices, from computers to radio receivers and various other electronic gadgets. Very few people even think to consider this. Most stuff just gets tossed away and replaced, of course at a much greater expense.

Good luck to you however you decide to resolve it.

Wagonman - if I end up ditching it, the dash control is yours.

Gregte - thanks for the encouragement. I just got off the phone with tech support and they had me do a couple of things (I'm posting this just in case someone else finds this via Google):

1) ensure the unit's LED is blinking with it switched on and the engine running (if you're using the ignition method for input (vs. VSS or magnet kit).

That checked out OK.

2) disconnect and ground the purple wire from the brake switch to ensure it's not the culprit (the LED on the cruise control unit will light when the ground circuit is open)

That checked out OK.

3) ensure the engine is producing enough vacuum (14-20 inches of mercury required for the unit to function). My ScanGauge MAP values showed the car is producing enough vacuum under load. (1 inch of mercury = 0.49109778 pounds per square inch, thanks, Google)

Checked out OK.

At this point, the tech said I'd have to send the unit in. I'll open it up anyway and see what I can see. I don't have a signal generator to do any testing (hmmm, I do have the car...), but I'll at least visually inspect it.

Well, I took apart the cruise control today and learned a little about how it works. Cut to the chase: I need to send it in for repair, or get a new circuit board.

There are three solenoid/check valves to the unit's vacuum chamber which contains the diaphragm / throttle cable.

The first thing I did was ensure the diaphragm & chamber seals are good, connected directly to engine vacuum.

Next I verified all 3 solenoids work when energized directly with 12v.

One labelled "vac" is normally closed and sits between the vacuum line and the chamber. When energized, it permits vacuum to the diaphragm/cable. The other two are normally open release valves, one labelled "vent" (fine throttle control), and the other "dump" (brake press, probably).

With the engine on & the unit engaged, the board is properly energizing (closing) the vent & dump valves, ensuring the reservoir is sealed. But when I press the "set" button, the vac solenoid only energizes weakly, on & off randomly, and doesn't permit enough vacuum through to the reservoir/diaphragm. The DMM shows only low voltage (less than 2v) on the vac solenoid, where the dump/vent solenoids are energized at 8v+.

The circuit board looks OK, but there's obviously something wrong with it. I guess the next step is to call Audiovox and find out if they can fix it, or send me a new circuit board.

Well, you *could* touch all the solder joints with your iron (got that idea from awillard) and see what happens. Then take resistance readings in circuit on all the resistors and make sure the resistors are at MOST their indicated value.

I have an aftermarket CC that sounds similar to yours regarding the solenoid controlled vacuum valves. It also had 3 of them configured how you have surmised, i.e. one is used for a 'dump' when brakes are applied while one is used for the normal realease of vacuum as required.

Anyway, to make the CC keep the vehicle closer to the set speed I connected the two solenoids together in parallel that release vaccum. This way they both dump when the brakes are applied and they also both release vacuum as required for normal speed control. This has the affect of releasing the gas pedal more aggressively when you top a hill and the throttle needs releasing, thus keeping the speed closer to the actual desired, set speed.

The same could be accomplished by drilling out the tiny hole in the vacuum hose fitting that air must pass through, but electrically paralleling them was more easily reversable than filling in a hole I might drill too large.

Gregte - that's an interesting mod. My unit actually came with two "responsiveness" settings, programmable via dip switches. One seems to be for time delay sensitivity to speed changes, and the other is for the "amplitude" of the response to speed changes.

dcb: I may just do that with the soldering iron. Little project for tomorrow. Plus I'll call Audiovox and find out if they'll just sell the circuit board in case I can't make it go.

Since youre not getting 12v to the solenoid, but youre getting something, a cheap fix might be to wire a relay to it. Of course, it might be a temporary fix since whatever is failing is bound to fail the rest of the way eventually.

Another thing to check would be the quality of the wiring to the solenoids unit. Maybe check the resistance of the actual wires? What Ive experienced several times is wires nearly broken inside their insulation. If you test it with a multimeter, it actually shows a good voltage. But put load on it, and it wont pass the current and wont function the device. Ive had this 3 times with my fuel pump relay wiring, and once with the headlights on someone elses Cherokee.

Thanks for the advice. The solenoid plugs directly into the circuit board, which tells me it's got to be one of the upstream components on the board.

I'm going to sheepishly admit that I boxed up the unit this morning to send back to Audiovox for repair. I called them first, but they won't just send me a circuit board.

At this point, it's just a question of available tinker time. I'd rather spend the time finishing up the Kammback than troubleshooting the cruise unit.

Update: Audiovox screwed up. I sent the unit in, and they sent me a letter telling me I had to include payment to get the repair, which I had done. They got it sorted out and are fixing it, but the downside was the delay meant I'm not going to get it back before going on holiday for a couple of weeks.

So, no more testing until late Sept.

FYI, Audiovox sent me a complete replacement kit. I'll be re-installing it today.

Hey thats cool, hope it ends up working well again.

I took it out for a test drive this evening, and the replacement unit seems to be working just fine.

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Someone asked me for the cruise control buttons in a PM or somewhere earlier in this thread. If you still need them, send me another note. I've got an extra one now.

Very cool. Great to hear that you are back in business.

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Yep that was me, earlier in the thread, and I still could definitely use that button pod. I sent you an email. Thanks!

So, anyone following the Kammback thread (http://ecomodder.com/forum/showthrea...sion-3518.html) knows the replacement cruise control quit working yesterday in the middle of ABA testing after less than an hour of use.

I had one more thought that I'll look at: I wonder if the problem could be a weak vacuum line between the "T" and the cruise unit. If the line is collapsing somewhere when the cruise actuator starts working, I wonder if it would shut down.

The tech guy on the Audiovox support line told me it required a minimum vacuum to work. I'm not sure if he meant the unit senses pressure and requires a minimum or it shuts off, or if he was just talking about a minimum needed for the diaphragm to physically pull in the throttle cable.

Hmm, thats a good thought. Maybe the extra hose to hook it up isnt as good of quality as the factory hose on the engine, and could be collapsing. Maybe you could go from where you teed into the factory line with a really short piece of hose, and cut a really short piece for the cruise unit end too. Then connect the two with something rigid like a piece of brake line with the ends cut off.

I have replaced pieces of vacuum line before and used hose for hooking up air shocks, with good results. Ive also tried stuff that was more like washer fluid hose, and it wasnt worth a crap for vacuum use.

Just wondering, does this cruise control have the "cancel" feature? I.E. you can disengage it without turning it off or resetting the memory. It does not appear to in the pictures I found but I just wanted to double check.

It cancels with the brake or the clutch. There's no actual "cancel" button on the interface.

Got a question about installation emailed to me, figure I'll post here for posterity:

I connected to the gas pedal because the instruction manual specifically said the OEM throttle cable must have a minimum travel of a certain distance, and the Firefly didn't. You might be able to get away with it, but I didn't even try. Worst case, the cruise unit might attempt to actuate the cable past the OEM limit.

I mounted the cruise unit on the driver's side strut tower under the hood, with the actuator cable pointed down.

I didn't drill any holes in the firewall: I routed the actuator cable through the speedometer cable firewall grommet into the cabin.

I clamped a long bolt to the top of the accelerator pedal arm, ABOVE the pivot point. That created a lever, the length of which is enough to get me the minimum travel for the actuator cable.

The actuator cable comes through the firewall, turns 180 degrees in a generous arc that doesn't bind the cable. It's held in place by fashioning a bracket from the parts that came in the box.

So the actuator cable actually pulls the top of the "lever" toward the rear of the car to press the gas.

Having posted all that, the replacement cruise control I got still doesn't work.

I need to replace the replacement before the summer so I can get back to doing "as controlled as possible" tests using my car.

As to my question about CC cancel, it dawned on me that this would not be very difficult to add. All it takes is a momentary switch in the wire that goes to the switch on the brake pedal arm. Stepping on the brake pedal is the only "cancel" available on a CC without a cancel button. I plan to add one to my car.

Called the company again today. They asked me to run through the same troubleshooting checklist for this second non-working cruise control unit.

I asked them if they kept records of return failure analysis - wanted to know if they could tell me what was wrong with my previous unit. They don't.

Anyway, I'll run this one through the gauntlet and probably end up getting a warranty replacement this time (since it's less than 1 year old).

Can't help myself here, sorry. But I'm sure an atmega with a vss tap and a mosfet or two could fix it too :) Add the injector tap and dial in the mpg you want ;) (within reason)

I'm sure it could be fixed/converted.... by someone smarter than me with ye olde electronics. :P

Searching for info about the Audiovox ccs-100 and how to fix it, I came across this thread and it gave me the impetus to open mine up and see what was what. I thought I'd post my results here for posterity as an expression of gratitude to this thread.

My cruise control wasn't working. The lights on the controller all seemed OK, and when I went through the troubleshooting steps in the manual, everything checked out. The LED flashed when the unit was on with the van running and increased in speed with the speed of the engine. That was all good. Next I checked the vacuum. I pulled the hose off the actuator and heard the vacuum release. So that was fine too. Next I took the case of the actuator apart. First I removed the rectangular service cap and pulled the 9-wire connector free. Then I took the metal bracket off the case, then used a flat screwdriver to undo the four tabs that held the back part of the case on (the part that surrounds the circuit board). This revealed the solenoid valves as well as the entire circuit board. The valve unit just pulls out of the circuit board. With the valve unit out, I tested each of the solenoids by applying 12V DC from a generic wall-wart transformer. Two activated, the other did not. The one in the middle seemed to be stuck.

I pulled the center solenoid out of the valve unit (after removing the little rubber strip) to tinker with it. Well, long story short, the spring that holds the valve closed was too strong for the solenoid to overcome. The solenoid must have become weak for some reason. There is a little metal plug on the bottom of the solenoid that can be pried out with a small screwdriver. It holds the spring in. I shortened the spring by about 1/16 inch by cutting off the last loop or so with a pair of side cutters. Put it back together and retested it. It worked fine. Put the whole thing back together and took it for a test drive, and everything works fine now.

Don't know how long it will last, but it works for now. Hope this helps someone.

bkeese: thanks very much for posting that info. It may help me when I finally get around to looking into this again.

Other new info I've learned since my 2nd unit failed (which I still haven't fixed/replaced):

- if the unit isn't receiving a high enough voltage, it won't work properly (one owner told me he fixed his by bypassing the brake cancel switch and wired power directly to the unit - with obvious safety implications). He did this after measuring the voltage at the unit and seeing there was a noticeable voltage drop when wired to the brake light circuit.

- the tech I spoke to told me the unit would work more reliably using a VSS signal instead of the coil signal (which is what I'm currently using)

Thanks bkeese,
That's what was wrong with mine. The middle solenoid was stuck. I took that solenoid apart and sprayed it lightly with silicone. I also cut a little off the spring. (You wrote a very nice tutorial)
And it's working. It only took 1 hour.
You saved me $100 on a new one.
Thanks again.

Well, it only worked for 1 hour. The solenoid is still bad.