cruise control question

[wklink]

My 79 GMC came with the single button cruise control.

Is it possible to switch it over to a more 'modern' style of cruise control or will I have to rewire the entire thing. I am not particularly happy with the cruise setup in the truck now. I know I should be happy I even have something this old with cruise control but I would like to convert it over to a later model system.

Thanks.

[GMC Jim]

what features are you looking for that you say is available in the newer systems ??

[bmartin9122]

The original cruise is strictly a set-speed brake-off type. I have this also. The newer systems offer accelerate/resume and coast/set.

[bmartin9122]

BTW, I see both of you are site supporters. How do I become a supporter?

[Srubydo1986]

Originally Posted by bmartin9122

BTW, I see both of you are site supporters. How do I become a supporter?

go to usercp (its at the top center of the page). it will take you to your page made just for you. On the left hand side down in misc. it says paid subscription. Click on that it will take you to a page were you can pick which kind of supporter you want to be.

Hope this help you out.

[GMC Jim]

sorry, can't help you on this speed control issue.... The speed control features you mention are all available in the after-market control I installed in my '71 GMC over 10 years ago....The control I have is manufactured by Rostra. You can google Rostra and I believe they have an 800 number which you could call to possibly upgrade your speed contol.... also you might check with a knowledgable parts guy at a Chev dealership... There might be available a control to your liking from a later model truck in your local junkyard

[bmartin9122]

Originally Posted by Srubydo1986

go to usercp (its at the top center of the page). it will take you to your page made just for you. On the left hand side down in misc. it says paid subscription. Click on that it will take you to a page were you can pick which kind of supporter you want to be.

Hope this help you out.

Thanks.... done!

[ocbaud]

my cruise control never worked since i've had my truck. during the engine swap i yanked out all the cruise control parts. i dont think it would have worked well with my setup anyhow.

yeah, i know this isnt related to your post, sorry

[bmartin9122]

Originally Posted by ocbaud

my cruise control never worked since i've had my truck. during the engine swap i yanked out all the cruise control parts. i dont think it would have worked well with my setup anyhow.

yeah, i know this isnt related to your post, sorry

Neither are my posts about being a site supporter, but at least you are keeping the thread active!


To add to the thread.... I am still waiting on a new cruise control transducer from Rock Auto. Hopefully, that will solve the erratic behaviour I have been experiencing lately.

[Zilverado]

Originally Posted by bmartin9122

...To add to the thread.... I am still waiting on a new cruise control transducer from Rock Auto. Hopefully, that will solve the erratic behaviour I have been experiencing lately.

Just curious - what kind of "erratic behaviour" you are experiencing. My cruise works fairly well, except for a slight (but pretty well constant) fluctuation in speed. Not enough to notice on the tach or speedo, but enough to feel it.

What/where is the "transducer"?

[bmartin9122]

Originally Posted by Zilverado

Just curious - what kind of "erratic behaviour" you are experiencing. My cruise works fairly well, except for a slight (but pretty well constant) fluctuation in speed. Not enough to notice on the tach or speedo, but enough to feel it.

What/where is the "transducer"?

The erratic behaviour is similar to your experience, but more extreme.

Once the speed is set, the truck will surge and coast on flat (0% grade) roads randomly. Since I have already replaced the brake light switch, I am attributing this undesirable performance to worn-out vacuum diaphrams or faulty electronics in the transducer.

The transducer is the primitive brain controlling your speed. It is located on the wheel well near the firewall on the driver's side. The speedometer cable enters and leaves it, as well as, several vacuum lines, and one 2- or 3-wire harness. It is a complex little beast.

[Zilverado]

Thanks for the info man. Good luck with your repair and let us know if it works for you. This is a minor issue on my truck, but I would LOVE to have it working well again.

What's the transducer worth?

[bmartin9122]

Originally Posted by Zilverado

...What's the transducer worth?

A-1 CARDONE 36101 (36-101) Cruise Control Transducer Reman

$79.79
+ $5.00 core
------------
$84.79 plus another $10 shipping (www.rockauto.com)

[Zilverado]

Thanks again - - like I said, keep us informed.

[bmartin9122]

n. p.

[bmartin9122]

Here are a couple of pics of my transducer replacement today:

the old one:



the "new" one:



gotta clean the speedometer cable:


reman installed: (Is it me, or does the lower cable look different in the after photo compared to the before photo? Cross-threaded?)


Now, I just have to figure out why it isn't working....hmmmm...
I guess I'll check fuses tomorrow. Who knows - maybe, I shorted something.

[Zilverado]

Originally Posted by bmartin9122

...Is it me, or does the lower cable look different in the after photo compared to the before photo? Cross-threaded?...

I would say "yes" it does look cross threaded - the cable is not as far into the transducer on the new one. Before spending too much time chasing a "short", take another look at this connection. Get the fitting on there straight and ensure that the cable is fully engaged. Could be this is why it's not working - cable not turning.

Or does the speedo work, but just not the cruise? If the speedo is working, then the cable is obviously engaged enough to work.

Either way though, I would try and get that cable fitting on there better.

[Zilverado]

BTW - Thanks for the update on the transducer. It turns out that my current truck (an '86) does not have this type of system - at least not that I can see. I believe my '77 did. The speedo cable on my '86 runs directly under the fire wall and back to the tranny. I have not crawled under yet to see if the cable goes directly into the tranny or through some form of transducer. Maybe I'll get a chance ot check tonight.

So my issue might be different than yours...

[bmartin9122]

Originally Posted by Zilverado

I would say "yes" it does look cross threaded - the cable is not as far into the transducer on the new one. Before spending too much time chasing a "short", take another look at this connection. Get the fitting on there straight and ensure that the cable is fully engaged. Could be this is why it's not working - cable not turning.

Or does the speedo work, but just not the cruise? If the speedo is working, then the cable is obviously engaged enough to work.

Either way though, I would try and get that cable fitting on there better.

I agree with you. Regardless, whether or not the cable is the culprit, I still need to check that. It may be engaging the speedometer inside, but not some other electrical component related to the cruise control.

I know I have good vacuum. I checked both control wires, and I never got any voltage from either one. Hmmmmmm.....

[Zilverado]

Yeah, unfortunately I am completely clueless when it comes to how this system is actually supposed to work (i.e. voltages, etc). And unfortunately, my system is different than yours (transducer anyway). Otherwise I could check and compare your voltages/results with mine.

Just a question about your vacuum... I assume you have a vacuum device that holds onto your throttle - don't know what it's called. Did you check the vacuum on this? If so, can you explain how you did this to determine that it was OK?

Thanks.

[kikkegek]

Originally Posted by Zilverado

BTW - Thanks for the update on the transducer. It turns out that my current truck (an '86) does not have this type of system - at least not that I can see. I believe my '77 did. The speedo cable on my '86 runs directly under the fire wall and back to the tranny. I have not crawled under yet to see if the cable goes directly into the tranny or through some form of transducer. Maybe I'll get a chance ot check tonight.

So my issue might be different than yours...

I got a cruise control manual with troubleshooting from somebody on here for a El Camino 84-87 model and I am pretty sure we got the same model.

Sent me a PM and your emailadress and I'll sent it over.

Haven't gotten around myself to test mine.

[hatzie]

Originally Posted by bmartin9122

I agree with you. Regardless, whether or not the cable is the culprit, I still need to check that. It may be engaging the speedometer inside, but not some other electrical component related to the cruise control.

I know I have good vacuum. I checked both control wires, and I never got any voltage from either one. Hmmmmmm.....

You have vacuum so check that one off. Make sure the servo isn't leaking.
If the Speedometer works the cables are connected good enough to spin the governor.
The transducer body needs to be well grounded. Usually the inner fender is a good ground.

There are actually only 4 wires in the whole cruise system.

12volts from the fuse panel to the brake pedal switch. PINK wire.
12volts from the brake pedal switch to the column switch. RED wire.
Two wires to the transducer from the column switch.
WHITE wire engage.
BROWN wire hold.

You should have power to the hold terminal any time the ignition is on. Fix that problem first.

The under dash cruise control power wiring is extremely short. It's a PINK wire that plugs into the front of the fuse box runs directly to the switch on your brake pedal. After the Pedal switch it goes to the steering column button via a RED wire. It's an add on harness so it probably does not mix with the main wiring harness.

When the switch is out, only the "hold" terminal should be powered. In this position you should have continuity from BROWN to RED at the switch harness under the dash. This is the idle or hold state.

When you push the stalk button all the way down, power is cut off to all wires. This kills the set-point. The way the terminals are located in the switch "hold" could be connected to "engage" but connecting these two wires doesn't do anything.

When you release the button the switch passes a point partway up where it energizes "engage" and "hold" at the same time. With the switch unplugged on the column you will have continuity on all 3 wires from the switch with the plunger partway between the bottom and top. This engages SET speed. It's imperative that all 3 positions work as designed.

There are some items that are internal to the cruise controller:
1. A low speed switch that opens below 35 mph to prevent cruise from engaging.
2. A mechanical governor driven off the speedo cable.
3. A variable vacuum orifice valve to control the cruise control throttle servo.
4. A solenoid coil that sets the speed by connecting (2) to (3), closes contacts to latch in "hold" power, and also control a vacuum dump valve. It's a very busy solenoid.

Leave the controller until last. If you can get power to "hold" and "engage" when you want it that's the hard part. It's then narrowed down to the transducer/controller. You can find a known good one and swap. From the wiring diagrams, it appears the transducer/controller body needs to be grounded to work.

This is an edited post from an F body board on the early cruise control setups.

[rcbildr]

IIRC the dieselplace website has a write up for installing a newer electronic cruise control from a chevy van.

[bowtiemanchevyman]

you want it to work like the new ones do right. what im going to do is take one off a 90's suburbun. my 90's has the type u want, accel, resume and ... so i figured it run off a cable and nothing is hook up to the any sensors so it will work on my 82 so it should work on your truck too. if thats what you are looking for.

[78 Chevyrado]

I have that old transducer type on my 78, replaced the transducer a couple of years ago and it works great, The only feature I miss that newer cars have is "RESUME" and the "ACCELERATE". I miss resume the most though.

This system will decelerate though, you just hold the button till you get to the lower speed you want and release.

Sorry the pics so big, but here's the instructions that came with my truck when it was new for the old transducer type cruise control. this tag came ffrom the dealer hanging on the turn signal stalk. This was a dealer installed item.