I've been going through my '69, taking care of several nickel/dime issues and everything is going along well, with the exception of the factory cruise control and it's turning out to be not so nickel-dime! Does anyone here know of a business or person that can rebuild or repair the transducer on my '69? Here's what I have discovered with the transducer. The solenoid coil resistance between the hold terminal (brown wire with white stripe) to ground measured 10 ohms. According to the CSM, it should read between 5 to 6 ohms. The CSM goes on to say a reading of more than 7 ohms shows excessive resistance and the transducer needs to be replaced. Trouble is, no one has a transducer to replace it so it appears the only option is to somehow rebuild it.

I did the other electrical checks using the CSM as my guideline. I found out the electrical brake release switch is bad. The electrical portion to the brake lights works but the part that goes to the cruise control system is inoperative. I also found out the cruise control wire harness is not good and needs to be replaced as the resistance in the brown/white stripe wire is too high - it measures 52 ohms and it is supposed to be between 42 to 49 ohms. Someone years ago (before I bought the car in 1987) replaced the last 9 inches of the harness that goes to the transducer with a piece of harness that has an incorrect wire for the brown/white stripe wire (the brown/white stripe wire is single strand; the replacement wire was multi-strand and I suspect that's what caused the increase in resistance). Fortunately, both the brake switch for cruise control and the wire harness are available in reproduction, even though replacing the cruise control wire harness is going to take some serious contortions under the dash to complete..

The "engagement switch" (on the column) is good and the switch on the dash is good.

My cursory look at the vacuum system shows it is working as it should (the "power unit" - I call it a diaphragm - holds air and the vacuum release valve at the brake pedal arm works as it should.

I'm wondering, with replacement of the items that I can replace, if the cruise control system will work despite the higher solenoid coil resistance reading (10 ohms vs what should be 5-6 ohms).

Any help will be greatly appreciated. I sure would like to get the factory cruise control system working again.

Randy C.

 

Randy, can you post or send me a photo of your transducer? I've collected several over the years but am not sure what all they came off of now. If I've got the correct one I can send it your way for you to test.
John

Ooops! And a picture of the brake switch.

 

Randy,
First of all, how accurate of an ohm meter do you have ? The readings you are getting might very well be fine. Maybe if 2blu has one he can compare the readings to what you have. They are well within most normal electronics tolerances. I would fix the obvious broken pieces first and then see if it will work.

 

I agree with Bill, verify your meter is reading correctly and also take the lead resistance into account. Low resistance (under 10 Ohms) can get tricky as you need very good connections - just a little bit of contact or lead resistance can end up being a significant portion of the measured circuit. At work I use a 4-wire meter that also has a zero offset correction, but a typical handheld meter doesn't have that capability.

Thinking about a solenoid - it's an electromagnet made by coiling a wire around a core material, so it's essentially just a length of wire. I don't really see how the resistance of the coil can increase. It would seem more likely that some sort of connection, terminal, etc could have some corrosion / oxidation that could result in increased resistance. For a length of wire to increase in resistance, the wire diameter (cross sectional area) would have to decrease.

 

Hi John, I'll get pictures to you via personal email tomorrow afternoon!

Hi Bill! I have a multimeter that is mid-80s vintage. I've tried newer multimeters but I just seem to be able to better read the actual meter than a bunch of digital numbers. I do zero out my multimeter every time I use it so I'm hoping the readings are as close to correct as possible. I can change scales so it appears to give me an accurate reading. But...being an older meter, it's possible that I'm not getting the accuracy that I need. I'll work with 2blu442 (John) and we'll see what happens!

Randy C.

 

I would double check the readings with a digital multimeter.

 

Member tdhill01 posted this link a while back
https://redirect.viglink.com/?format...se_Control.pdf

 

So, I went back to my old style analog multimeter and figured out I was using a scale that would not give me a real accurate reading so I went to a scale that would be more exact and saw that I had to zero it out again before I used it. When I did, I got 9 ohms of resistance with the transducer (book says 5-6 ohms is what it should read). I also took two measurements of resistance on the brown/white stripe wire. The first one was from each terminal, which included the patched in 9" of multi-strand wire with the stock/original single wire in the harness and I got 45 ohms. The second measurement came from the stock single wire (removed the 9" multi-strand wire extension) and it came in right at 42 ohms. The book here called for 40 ohms, plus or minus 2 ohms. So the single stock/original wire measurement hits the mark, and it stands to reason that the extra 9" of multi-strand wire included with the stock harness is going to increase the resistance. There is extra stock/original single strand brown/white stripe wire in the harness that I could potentially bring out and crimp into a new blade at the connection to the transducer so I'm looking into that now.

One other thing that has me baffled is that there is supposed to be an in-line fuse in the dark brown wire that's part of the harness under the dash. I have yet to find it. It looks like not only will the A/C ducting have to come out, but the heater box as well. What fun!

Randy C.

 

CSM fig. 15-37 shows no in-line fuse in that circuit. Wire goes straight to fuse box. Thus fused.

 

Thanks for the heads-up on that. What throws me is, when I look at a picture of the replacement harness, there appears to be an in-line fuse in the brown wire that goes to the fuse box. I'll have to take a closer look at what's going on there.

Randy C.

 

Randy, I have a 1969 Vista Cruiser project car that has cruise control. I haven't looked at it in a long time, but if the harness hasn't been hacked I could take some photos for you. Let me know if that would help. Oh yeah, I guess I didn't need the photos from you after all if its the same setup!

 

Wow, John, that would be great! The harness, the brake switch, and the transducer should all be the same. If things look good and if you aren't planning on using them (I don't want to mess up a car you want as a project), I could plan to come down your way and test those items and extract them if they prove worthy! Let me know what you think! Best Regards, Randy C.

 

Randy, I'm still hoping to restore the 1969 Vista Cruiser even though its got a lot of rust compared to other cars I've drug home. But... I just took the time to compare your photos with the Vista Cruiser and it looks like someone's replaced the transducer with a newer one and modified the wiring to match it. I spent a little time poking around the garage and located a brake pedal switch but will need to dig a little deeper in the parts collection to see if I can find the correct transducer. I hope to do that this weekend so I can let you know the beginning of the week what I have.
John

 

That's great, John! I greatly appreciate the help. Looking forward to seeing what you find!
Best Regards,
Randy C.

 

With the two-wire harness that goes to the transducer on a '69 A-body car, which wire goes where? There is a light brown wire with a white stripe and a black wire. These wires fit into a "T" shaped connector that plugs into the transducer. I need to know which wire goes into the top part of the "T" and which wire goes into the bottom part of the "T".

In pursuing the cruise control problem (it doesn't work!) on my '69 4-4-2, I found that the electric portion to the cruise control on the brake switch was inoperative. Thanks to 2blu442 and his wonderful supply of Oldsmobile parts, I was able to get another brake switch and correct that problem! The engagement switch (button on the column) checks out per the CSM. I've checked the electrical all the way to the transducer and I get 12V through the brown/white stripe wire when I engage the column switch (I presume this is what is called the "engage" wire?) and it disconnects when I press the brake pedal. I'm guessing the black wire is a ground? As well, I've double-checked all the vacuum lines and they are intact. The power unit/diaphragm mounted on the intake manifold holds as it should, and the vacuum release valve at the brake works properly.

I just want to make sure I've got the connector wires into the transducer correctly before I take it on a test run.

Many thanks! Randy C.