I'm posting this problem in the general discussion section rather than the technical section because I see a recent , similar post here by fellow member Roy Schroeder . My 76 Eldo's cruise control doesn't work either . First , is the cruise control in my 76 the same set up as Roy's 78 ? If it is , I'll print out the responses to Roy's post , give the information to my restorer , and save everyone the time of repeating information for me . Second , let me try to explain what my restorer has told me . This stuff is way out of my league , but I'm sure some of you will know what he is talking about . He said he thinks the problem may be in the "transducer" - a unit which is attached to the firewall that has a wire entering it from the transmission and another wire exiting it and going to the speedometer . He said the service manual states that the "coil in the transducer "( his words , not the manual's - I guess some people refer to it as a solonoid ) is supposed to register 6.0 ohms but mine registers only 0.5 ohm . I hope I'm relaying this information correctly . So ... does it sound like this unit might be the problem ; and if it is this unit , can it be repaired/rebuilt or must I go junk yard hunting ? I'm waiting for J. Pinto to respond to that same question in case someone planned to suggest his name . Thanks for any help . Paul Tesone CLC #6876
Paul, I can tell you that the 76 and 78 are different. As far as the testing of the coil, you would be better off getting a repair manual for your car and reading up on it, if you cant get an answer here.
Roy
I looked up your part number for the transducer. Google it.
Group 3.885 Pt 25030712
It also states that the 2 or 3 prong terminal ones will work. If yours has two, it just says the disregard the third prong.
My parts books go from 76 to 80. My repair books are only for my car. Sorry.
You also could check with Cadillac Tim.
He reworks alot of parts.
Roy
http://www.cadillactim.com/index.html
Page with transducers.
http://www.cadillactim.com/page9.html
Found this on Ebay. NOS
http://www.ebay.com/itm/1970-1971-1972-1973-1974-1975-1976-CADILLAC-CRUISE-CONTROL-TRANSDUCER-NOS-GM-/390384692619?pt=Motors_Car_Truck_Parts_Accessories&fits=Year%3A1976%7CMake%3ACadillac&hash=item5ae4bdad8b&vxp=mtr
Roy - what great information ! I called Cadillac Tim and ended up buying a rebuilt transducer from him. I was tempted to go for the NOS one that you told me about , but Tim's was much less money . I figured that if my guy was incorrect about the problem being the transducer , the mistake wouldn't be as costly . It should be here by the end of next week . Can't test it out before next weekend anyway due to predicted bad weather . I'll let you know what happens . Thanks so much ..... Paul Tesone CLC # 6876 .
Glad it worked out for you.
Roy
About the only trouble I have had with that style system is the grease (or what ever the factory lube was) gets hard in that little gear box. I have had them actually seize up. One car it stripped out the gear in the transmission. The other it just broke the cable. Its not a bad idea if you are working around your car to unscrew the cable that goes down to the transmission and use a small screwdriver to spin it to make sure it spins easy. There really should be no drag. If it is stiff maybe Tim has some tips on how it can be lubricated? I took one apart once and did get it lubed but must have broke something because the cruise didnt work. At least I got it to spin freely so my speedo worked again.
Thanks TJ - I'll pass that info along to my restorer . Paul Tesone CLC #6876
Just as a point of reference, Auto Zone still has (got one three weeks ago) a (Cardone) rebuilt cruise control transducer for just about $100.00.
What I have found however is 4 to one, most of the issues regarding cruise control operation are either bad electrical connections, leaks in the vacuum lines, or bad (or mis adjusted) switches on the brake arm.
Greg Surfas
Thanks Greg - more good information for my restorer . As mentioned above , I've already purchased a rebuilt one and I'm expecting delivery the end of next week . Let's hope my restorer made the correct diagnosis and that the rebuilt unit works like it's supposed to when installed . I'll let everyone know once it's tested . Thanks , Paul Tesone CLC # 6876
I too am having problems with my cruise control on my 76 Eldorado. So far I have replaced the dash switch with a working used one. I have also replaced the transducer. After doing the test from the shop manual I can hear a click noise and the green cruise light shines. Now, after I undo the test connection and installing it properly nothing happens. I see that there is some sort of resistor wire? That part I do not understand. I am very lost here.
thank you
Just in case: maybe this is the turn signal lever which has a problem. I have a NOS one, used from 1974 to 1976 for cars with T & T steering column. Part number is 1603586.
Back to the shop manual. This is so well written any restorer should have no problem repairing a cruise control unit with careful reading and following directions. All of the components you might need to replace to get the system working are not expensive. I have repaired about five of them from 1967-1976 years. The 1967 is much different (1970 thru 1976 similar).
Don't forget to use a vacuum pump and test the actuator linked to carb throttle. Often that ruptures and is no good, used is only way to go in that instance. As a general precaughtionary measure, all vacuum hoses (especially the one that penetrates firewall to brake switch) should be replaced if not already recent and all electrical connections should be cleaned and checked.
The problems I have seen are:
1. bad vacuum actuator
2. bad transducer
3. Good vacuum hoses, but installed wrong and kinked (cut too short, did not allow enough for bend)
4. bad vacuum hoses
5. adjustment on brake switch required after brake work
I'm sure there are means of failure. When you find the problem, still clean electrical connections and replace old vacuum hoses so it will work for a while.
Great information to check out. It turns out that owner before myself had removed the lower speedo cable and took the upper cable directly to the (speed sensor) trany connection. Thus by passing the cruise control transducer all together. I am sure the FSM shows that in it but I could not find it. The FSM is not the easiest to search through or find needed information. (my experience )
Quote from: cadillacrandy on June 13, 2016, 10:02:34 PM
The FSM is not the easiest to search through or find needed information. (my experience )
Wait tell you try to look something up in a manual for a modern ‘puter car.
The FSM is very well done for the cruise control on the 1960-1970 Cadillacs, there should be no trouble following it. The FSM are available on e-bay for around $40, well worth it.
CadillacRandy, what year and model car do you have? If we know that we can give you some pointers on where to look on the car and or in the manual. If its been bypassed you would want to make sure the unit is still able to turn freely before trying to hook it back up. You don't want to damage anything like the gear in the transmission.
I was looking at the cruise on my '76 today. I'm looking at the vacuum diagram in the service manual to see the proper hook up but its not clear as to which ports on the transducer that each hose is hooked to. I'm looking online for an actual picture in the car
Quote from: R Schroeder on June 02, 2012, 03:15:25 PM
I looked up your part number for the transducer. Google it.
Group 3.885 Pt 25030712
It also states that the 2 or 3 prong terminal ones will work. If yours has two, it just says the disregard the third prong.
My parts books go from 76 to 80. My repair books are only for my car. Sorry.
You also could check with Cadillac Tim.
He reworks alot of parts.
Roy
http://www.cadillactim.com/index.html
Page with transducers.
http://www.cadillactim.com/page9.html
ROY! Do you know if Cadillac Tim is still in business. I just can't get to his web-site. The address you stated above was the old one and doesn't work anymore. If you have his new site, if he's still in business, I'd appreciate it. Thanks! EAM
Cadillac Tim has been discussed in these forums several times recently. Tim himself has posted that he is still in business --- with his phone number --- 864-348-7732, just a few days ago. Apparently he has let his website go. His phone number is also readily available at the MCLC forums --- http://www.modifiedcadillac.org/ --- in the thread titled ---
"NEW Huge List of Cadillac Parts Vendors"
Re: Cadillac Tim is the man for 67/68 Caddie
« Reply #7 on: May 20, 2017, 09:49:09 PM »
Yes, I'm still in business. My work phone is 864-348-7732.
Tim
Quote from: Paul Tesone on June 02, 2012, 02:33:35 PMI'm posting this problem in the general discussion section rather than the technical section because I see a recent , similar post here by fellow member Roy Schroeder . My 76 Eldo's cruise control doesn't work either . First , is the cruise control in my 76 the same set up as Roy's 78 ? If it is , I'll print out the responses to Roy's post , give the information to my restorer , and save everyone the time of repeating information for me . Second , let me try to explain what my restorer has told me . This stuff is way out of my league , but I'm sure some of you will know what he is talking about . He said he thinks the problem may be in the "transducer" - a unit which is attached to the firewall that has a wire entering it from the transmission and another wire exiting it and going to the speedometer . He said the service manual states that the "coil in the transducer "( his words , not the manual's - I guess some people refer to it as a solonoid ) is supposed to register 6.0 ohms but mine registers only 0.5 ohm . I hope I'm relaying this information correctly . So ... does it sound like this unit might be the problem ; and if it is this unit , can it be repaired/rebuilt or must I go junk yard hunting ? I'm waiting for J. Pinto to respond to that same question in case someone planned to suggest his name . Thanks for any help . Paul Tesone CLC #6876
The whole story for me goes back to adjusting the brake/cruise switch at the pedal.
I think it has been misadjusted for some time, not having tried to use it for months after installing the brake booster.
I had a 1976 Cadillac Seville that had cruise control that wouldn't engage. No green cruise light and no engagment with the cruise control switch turned on and tap the engagement button on the end of the turn signal switch above 24 mph.
After going through the 1976 Cadillac Seville troubleshooting in service manual, I found that my transducer was bad (according to the manual) using a test light and further utilizing continuity function on my ohmmeter.
According to the service manual, one can pull and rotate the two pronged hold/engage connector, and connect the the 'black' wire normally connected to the 'engage' connector to the 'hold' prong with the key ignition on and the cruise switch set to on, and depress the engagement button on the turn signal lever halfway, so you should hear the cruise control transducer click, and the green cruise light should light, until one depresses the brake pedal, which should make the transducer click again and the green light should go off, signaling disengage of the cruise control.
I grounded the 'light' prong on the transducer to ground by backprobing the harness connector with a test light, and both the amber on and green cruise light came on on the dashboard switch for cruise control on/off switch, indicating a bad transducer (according to the service manual).
I also disconnected the small three wire harness connector under the dash with small black, brown, and blue wires on the end of the micro blue plastic colored plug that plugs into the black harness connector. I tested with a continuity function of my ohm meter with a couple of double ended small alligator clips from Harbor Freight Tools to test continuity with the button 1/2 pressed and fully depressed on the engagement switch on the turn signal lever. That tested out okay according to flowcharts in the repair manual.
If you can't see the contacts on the end of the blue plug, you can leave it plugged to the black harness connector and test the black receptacle by inserting the prongs of the ohm/continuity meter into the black, blue, and brown colored wires that enter the plug. One can test it that way, too.
I also tried to use a test light to supply power to the disconnected prong for hold and engage. No clicking sound.
I found a remanufactured/rebuilt transducer on ebay.com for about $200.
Update: I changed the transducer with a remanufactured unit, but it still did not cruise properly.
I am embarrassed to say, that I backtracked and found the brake light/cruise control combination switch was adjusted with too much play at the pedal. I had previously changed the vacuum brake booster out, and although the brake lights worked correctly, the cruise control portion of the switch was adjusted so it was sending a signal to the cruise control circuitry that the brake pedal was depressed, causing the cruise to not engage at all.
If I pulled up on the brake pedal and simultaneously 1/2 depressed the turn signal lever engagement button, and the green cruise light goes on momentarily, assuming the bulb is good, then everything is fine with the cruise control circuits except for the simple adjustment of the brake and cruise control combination switch.
In conclusion, my cruise control not engaging at all, can be traced back to a problem with adjusting the brake/cruise switch so the brake pedal barely rests on the button, as it returns under gradual spring pressure from the rod connected to the vacuum brake booster. It is better that the switch trigger brake lights and cruise control disengagement on an ounce of pressure pressed on the pedal by the foot, than to have it travel 1/2" before the brake lights go on and the cruise control disengaged. The brake/cruise disengagement switch on my car may eventually be replaced, but for now it works fine.
Note: I fixed the broken plastic vacuum T by replacing with a 5/16" black plastic vacuum T from local NAPA Auto Parts store.
'Elementary, my dear Watson'- Sherlock Holmes comes to my mind.