Vacuum modulator

[ranger88den]

Does a 1995 geo tracker 4x4 w/3 spd. auto have a vacuum modulator? If so, where is it located? Thanks, Dave

[HAWG]

yes it does have a modulator. should be located on the rear of trans on right hand side.

[ranger88den]

Originally Posted by HAWG

yes it does have a modulator. should be located on the rear of trans on right hand side.

Thank you for your reply. Do you know how to test it for proper operation?

[cheyenne'88]

Think all you do is remove the vacuum hose from the modulator, and if there's trans fluid, it's bad.
Check the hoses!
What's it doing?
When I've knocked the hose off, it wants to hold onto first gear way too long, plus some "seat of the pants" weirdness.
If I bump or move the hose at it's manifold connection, it pops off at the transmission connection. (hard line with rubber ends, on my Chevy)

[HAWG]

what sort of problem are you having?

[ranger88den]

Originally Posted by cheyenne'88

Think all you do is remove the vacuum hose from the modulator, and if there's trans fluid, it's bad.
Check the hoses!
What's it doing?
When I've knocked the hose off, it wants to hold onto first gear way too long, plus some "seat of the pants" weirdness.
If I bump or move the hose at it's manifold connection, it pops off at the transmission connection. (hard line with rubber ends, on my Chevy)

All my brakes are locking up. I have eliminated the RWAL computer. I am led to believe the vacuum booster system can cause this, either the hoses or the booster itself. Hoses test ok. After researching this a bit, it has been suggested that a bad modulator will leak fluid into the vacuum system, hence, deteriorating the booster diaphram. The author also said white smoke in the exhaust could be caused by the modulator leak, which I have. Thanks for everyones help. Dave

[cheyenne'88]

You can test the booster.
Vacuum Leak Test:
1.Let the engine idle for at least one minute.
2.Turn off the engine and wait one minute.
3.test for presence of vacuum assist by depressing brake pedal and releasing it several times. If vacuum is present in the system, light application will produce less and less pedal travel. If no vacuum, air is leaking in system.
System Operation Test:
1.With the engine OFF, pump the brake pedal until the supply vacuum is entirely gone.
2.Put light, steady pressure on the brake pedal.
3.Start the engine and let idle. If the system is operating correctly, the brake pedal should fall toward the floor if the constant pressure is maintained.

[cheyenne'88]

Chilton's book has quite a few pages dedicated to the RWAL system and diagnosis.
If you need, I can scan and send the section to you.
Lemme know!

There's also a section on getting the codes ffom the RWAL system and what they mean.

[ranger88den]

Originally Posted by cheyenne'88

Chilton's book has quite a few pages dedicated to the RWAL system and diagnosis.
If you need, I can scan and send the section to you.
Lemme know!

There's also a section on getting the codes ffom the RWAL system and what they mean.

Thanks again. I only have access to a computer about once a day so sorry for the delay in answering. I have the Chilton's manual, I guess I should read a little closer. I did check the RWAL computer and no codes. I will check the modulator and also Chilton's again this weekend. Appreciate the help. Happy Thanksgiving, DAve

[fellertact]

does a '91 geo tracker have a vacuum modulator?if not what is causing it not to shift into 3rd gear until it warms up?someone said it may be the servo.any ideas.i'm trying to sell this car.

[HAWG]

It wont shift out of second into third, or it wont shift from third to overdrive?

[fellertact]

doesn't have overdrive.3 speed

[HAWG]

let me rephrase it. It will not shift out of second into third, or the convertor will not lock up onto what we can consider an overdrive

[fellertact]

it won't shift from second into third until i rev it for awhile.than it shifts to third and it's fine until it sits for awhile.

[fellertact]

it's like it goes to nuetral than it'll shift to 3rd