Jump to content

91 cruise control vacuum fittings


Guest squiretom
 Share

Recommended Posts

Guest Squire Tom

hi guys , merry christmas

so begins my tale

had a bad leak in the side cover gasket of the tranny . checked several repair facilities and all had about the same price. on the way to the buke dealer i made a stop and when i returned to the vehicle i was leaking coolant.

long story short the buke dealer cracked a vacuum fitting for the cruise control during the tranny repair.

any one have any ideas regarding the parts needed ? did not get a real good description of the part from the tech and of course nothing available at the buke dealer. i believe the 91 is comfuser controlled as opposed to the earlier years. i will also send this to finn also.

the tech manager is also going to try to find the part , but the forum is probably a better backup.

thanks guys

Link to comment
Share on other sites

In the supply line to the cruise control servo, there's a vacuum "t" of sorts, with a check valve made into it. They normally crack at the right angle bend. The other side of the "t" supplies vacuum to the hvac system (IF it's vacuum controlled rather than electric servo motors) . . . when that system looses vacuum, the default mode is "floor air and defroster air" no matter what is selected. On my GM cars, it's also near the vacuum brake booster and the inner fender area.

You can probably find the same vacuum check valve/T item on the Help! rack at many auto supply stores. This was a very common "age-related" failure back then. Time, age, and underhood heat. The crack is a hairline, but can be enlarged by "outside influences".

Just some thoughts,

NTX5467

Link to comment
Share on other sites

If the vacuum line is leaking coolant, you have a different problem. Please be explicit about what is going on, the closest coolant line to the cruise control is the little tubes under the throttle body. I have also seen a leaking water neck spray water elsewhere.

Unless you are very fortunate and have one who cares & knows Reattae, I would not take a Reatta to a Buick dealer.

If you get to Orlando, bring it by and I'll take a look.

Link to comment
Share on other sites

Guest Squire Tom

sorry , forgot to mention the RADIATOR flumbulgated itself and had to be replaced with an aftermarket clone for $ 200 + . it just happened to be a good news bad news failure as it could have happened at some less opportune time.

ps i will check to see what climate control functions still work.

Link to comment
Share on other sites

Guest Squire Tom

the a/c works in all directions , so i guess they patched it somewhat. still searching for the correct part for the cruise vac servo. cruise light comes on but no cruise control function.

Link to comment
Share on other sites

Guest Squire Tom

was looking in the repair manual for a look at the part , but didnt see anything in the cruise section. can anyone with a 91 take a pic and either post it or send it as a private email ? from the info from the service tech , i might need a pic of both ends. as i mentioned the a/c works in all functions so it might just be the servo end .. or maybe not

sorry , that is the most info that i have

Link to comment
Share on other sites

Guest Squire Tom

stopped in to the buke dealer to see if they located the part. they have not looked very diligently. talked to the service tech and he showed me what happened. apparently the fitting ON THE SERVO was damaged, and that is why the a/c works. anyone know where i can get a SERVO for the cruise? i emailed Finn and so far no response. probably my fault from the lack of information.

the tech said he might be able to epoxy the fitting but didnt know how much it would cost! the tech said old plastic breaks and seemed like he was denying responsibility. i then talked to the service manager and he had a better attitude

and said he would try to help me out.

still need the servo.

Link to comment
Share on other sites

Guest Richard D

If the servo is the same as a 90 or older GM built millions of them, I am sure that Jim Finn or Marck at East Coast Reatta Parts can help. Check the resources sticky at the top of the forum.

Link to comment
Share on other sites

Things that are hard to change I buy new. Have swapped a cruise control servo in 5 minutes before. Same for 88-89, GM built millions. I often grab a couple when the pic-a-part has a 241 sale.

Thing is for me, I've found that most don't work. Dunno what goes wrong, but they just don't work. I just bypass the trouble and get a new one.

Link to comment
Share on other sites

I have to take issue with Marck's statement that they cannot be tested on a parts car.

Yesterday, I took one of my still drivable Reatta parts cars out on the road in front of my house and tested some cruise control servos. All were good. I did this not because of this post but recently I sent one to a lady in OK/TX and the repair place said it was no good. I am 99% sure it was good as in reading their diagnosis it is not the cruise solenoid that is bad but the brake pedal cutoff switch.

I am 99% sure the solenoid was good because it came off a car I was personally driving before I turned it into a parts car. In addition I tested the vacuum portion of that solenoid just prior to sending it out.

As of my testing yesterday I do have 4 cruise control servos available and sell them at my normal price of $ 25 plus shipping.

Edited by Jim (see edit history)
Link to comment
Share on other sites

When removing the cruise servo from the car you have to be very careful when taking off the larger of the two vacuum hoses. You can easily break the plastic fitting. I like to give the hose a twist to break it loose and then using a screw driver pry the hose off the fitting.

You cannot test the servo without having it on a car but you can test the vacuum side off the car by sucking in on the large vacuum port and the bellows should go in and stay in as long as you are sucking on the fitting. It doesn't take much to suck the bellows in, if it is good, but if you have to suck pretty hard then there probably is a hole in the bellows.

Link to comment
Share on other sites

Guest Mc_Reatta

It's not hard to test the servo to see if it will function electrically either.

The servo contains three large electrical coils inside. Two are used to open the vacuum and vent ports and the third is used to tell the BCM the movement and position of the throttle cable.

To verify that your servo is good electrically, use your DVM set to the lowest ohms range.

There are five prongs at the electrical connection. Using the DVM measure the resistance between the center prong and the two outer prongs. (1, and 3 and 3 and 5). Each of these should measure around 40 to 42 ohms apiece. Typically if one is bad it won't return any reading (open). If the reading is close but not quite within range, touch the two meter probes together and look at the reading. Most inexpensive DVMs don't allow the meter to be zeroed out, and will have a reading of a couple of ohms or so when this is done. This small error will be reflected in the reading of the coils and can be taken into account to see if the reading would then be within range.

If one of the readings is below 40 ohms and a meter error is not suspected, I would caution against using that servo as the circuits inside the BCM that control these solenoids are running close to maximum current, and if the resistance falls below 40 ohms, the extra current can damage the output circuit requiring the replacement or repair of the BCM.

Then take a reading between the second and fourth prong. This should return a reading around 20 ohms. If not the BCM won't be able to track the operation of the servo in and out.

If these three resistance readings are present, the servo should be operational electrically. If you have a DVM in your P&P toolkit, then you can verify them in the field, and if a visual inspection of the bellows and vacuum ports don't reveal any obvious issues, then the servo is probably fully functional.

Link to comment
Share on other sites

Guest Mc_Reatta
I would be interested in getting my cruise control to work once again. Don't know where to start. Anyone have a sequence of checks?

Waltmail, start by pulling any trouble codes from your system by using the procedure from Ronnie's site. How To Access Trouble Codes - '90 & '91 Models - ReattaOwner.com

If the servo has electrical issues there should be a cruise related code or two indicated.

Does the cruise control on light illuminate when you turn it on?

If there are no CC codes present, and the light turns on, then I would suspect that the system is a vacuum leak somewhere. It can be between the canister and the servo, or between the servo and the brake pedal vent switch.

If you can report back with whether it appears to be electrically related or vacuum related, we can help you track it down further. There are several BCM diagnostic procedures to test the electrical circuits and tips on where to look for vacuum problems too.

Link to comment
Share on other sites

Thank you for the information.

I will print it out and save it, saving time putting cruise units on one of my cars and road testing them.

It's not hard to test the servo to see if it will function electrically either.

The servo contains three large electrical coils inside. Two are used to open the vacuum and vent ports and the third is used to tell the BCM the movement and position of the throttle cable.

To verify that your servo is good electrically, use your DVM set to the lowest ohms range.

There are five prongs at the electrical connection. Using the DVM measure the resistance between the center prong and the two outer prongs. (1, and 3 and 3 and 5). Each of these should measure around 40 to 42 ohms apiece. Typically if one is bad it won't return any reading (open). If the reading is close but not quite within range, touch the two meter probes together and look at the reading. Most inexpensive DVMs don't allow the meter to be zeroed out, and will have a reading of a couple of ohms or so when this is done. This small error will be reflected in the reading of the coils and can be taken into account to see if the reading would then be within range.

If one of the readings is below 40 ohms and a meter error is not suspected, I would caution against using that servo as the circuits inside the BCM that control these solenoids are running close to maximum current, and if the resistance falls below 40 ohms, the extra current can damage the output circuit requiring the replacement or repair of the BCM.

Then take a reading between the second and fourth prong. This should return a reading around 20 ohms. If not the BCM won't be able to track the operation of the servo in and out.

If these three resistance readings are present, the servo should be operational electrically. If you have a DVM in your P&P toolkit, then you can verify them in the field, and if a visual inspection of the bellows and vacuum ports don't reveal any obvious issues, then the servo is probably fully functional.

Link to comment
Share on other sites

  • 2 weeks later...
Guest Squire Tom

any time i remove vacuum lines from plastic fittings , i use an exacto knife to slit the hose along the length of the fitting , comes off really easy with little chance of breaking the fitting. almost always enough slack to be able to reconnect. a little silicone spray helps in re attaching the hose.

Link to comment
Share on other sites

Guest Squire Tom

hooray for my buke dealer , they bought a NEW servo (advance auto ) and installed at no charge in a half hour. they squeezed me in at my convenience. it warms my heart to experience what a kind word and a 6 inch , rubber grip , nickel plated .357 s&w can accomplish during the holidays.

Link to comment
Share on other sites

  • 5 months later...

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share

×
×
  • Create New...