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Looking for someone with knowledge of 87 gl cruise control


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1987 subaru GL, standard 5 speed ea82 spfi. I purchased the car about a month and a half ago. Has cruise control.

 

Problem is cruise control doesn't work. Car also starts without clutch pushed down. I am assuming this may be the reason cruise does not work as I would think cruise would shut off with clutch pressed down. Not sure though as cruise didn't work when I purchased the car.

 

I have looked at the clutch switch and have not had time to test it yet, but it does seem to click when I press it in manually, and clutch pedal does seem to make contact with the switch as it it supposed to.

 

I have also checked the fuse linked to the cruise. Fuse is good.

 

I am hoping someone with some knowledge of the way the cruise system works can chime in. Thanks

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The clutch switch is only for the cruise control, nothing else.

Have you checked the 2nd switch on the brake pedal?

Does the cruise power up when you turn the system on? Get someone to do this while the engine is off and the hood up, you'll hear the pump start up to make air pressure.

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Check the vacuum line on the cruise unit (it's up under the dash, attached to the accelerator pedal with a length of bathtub stopper chain). The vacuum line goes through the firewall near there and routs under the spare tire to the R side of the engine compartment.

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I need to know if you have the dealer installed system or the factory.  Is your car a GL-10?  Does it have trip computer?

 

If not it is the dealer setup.

 

Suspects right off are Brake switch bumper, vac line to canister at pedal, and vac line to big round resevior mounted to passenger strut tower.

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I have no idea if it is dealer or not. I have all analog gauges, only thing to keep track of trip mileage is the tripometer. The switch to turn on the cruise in on the dash by rear defrost switch and the other cruise buttons are on the steering wheel, right side of horn button.

 

I will check the for the issues yall have mentioned and report back. 

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I just checked under the hood. I have a little black circle box with several wires that run to the other side under the hood toward the service and test connectors. Also attached to this box is 2 vacuum lines, one comes off the same vacuum line that run to other misc item on the motor the other runs to the other side of the engine compartment and seems to go to a drum on the gas pedal assembly.

 

So, i would guess there is not a pump for the vacuum on my car, instead it runs off the engines vacuum and the box maybe controls the vacuum to the cruise control?

 

Second thing under there is a little white cylinder, had a vacuum line in, and out. Same as the other black box except it has no wires running to it. The line is also very small, maybe an 1/8". Lines runs from it, then under the dash.

 

When i push in the cruise button on the dash, nothing seems to happen outside of the light on the button,

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  • 2 weeks later...

The white canister is a vacuum reservoir which is used by the heater box vent controls.

Do your vents work?

 

You've checked all these hoses are plugged in & not leaking?

 

Some pics would be really helpful you know. We're still not sure if you've got the factory fit or dealer fit version...

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I recently found out the white canister belongs to the ac system. My ac and vents work fine.

 

As far as the cruise control, I have checked all hoses, leading all the way to the gas pedal. I do not see any leaks and all hoses are intact.

 

An explanation of how the system actually works would be helpful, I posted in a previous post my assumptions on how it works. 

 

Also, previous owner said it worked fine, but on occasion he would have to pull up on the clutch with his foot in order for it to set.

 

IMG_20150623_1252361_zpssfov7jac.jpg

 

As you can see in the picture, vacuum line from engine feeds the box with the wires going into it. From there another vacuum line runs off it, that line runs into the cabin. It appears that same line is the one connecting to the gas pedal drum.

 

My assumption is that the box is some sort of actuator, when given power it open and allows vacuum pressure to go to the vacuum drum on the gas pedal. This electrical signal to the box is dictated by the press of the button on the dash and steering wheel and the switch and or switches on the brake and clutch pedals. 

Edited by grandam88
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how cruise systems usually work:

there will be an electronic brain somewhere.

it has inputs from the speedo, sometimes tacho, brake pedal, sometimes clutch pedal, an on/off switch, "set" & "resume" switches (newer ones also have a "cancel" switch. Newer versions also have a neutral switch.

output to the vacuum solenoid (in this case)

When on, and then hit set, the brain monitors the speedo to keep it constant. slow down and it will get the actuator to open more to suck harder, therefore pulling the gas pedal, accelerate & it does the opposite.

 

Mostly, the clutch switch & brake switch are normally closed switches in series so that when you hit either pedal, the circuit is broken, and the brain knows to deactivate the cruise.

 

The factory brain for these is over the glovebox on RHD models, don't know about the LHD versions.

 

he previous owner had to do that with the clutch, I'd suggest checking the rubber stop on top of the pedal to see if it's intact. The switch is on an adjustable thread. If that switch isn't closed, then the cruise won't "set" because it thinks you've got your foot on the clutch.

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I got to dig around under the dash this afternoon. The cruise control has both the clutch and brake switches(brake has two switches total). I did notice a mysterious green connector just disconnected hanging out under there. The rubber bumper was intact and appeared to be activating the switch, whether the switch is in working condition or not, I have no idea. My clutch pedal does seem to have play left to right though. 

 

I will try and check more into the clutch side of the switch with a DMM to see of all is working the way it is supposed to and go from there. I appreciate the help.

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green connector with no locking tab? If so, that's for the check engine circuit. Should be another one hiding in there somewhere to connect to it, but that's nothing to do with the cruise.

 

Check both the switches. When the pedal is untouched, there should be connectivity across the terminals.

Might be a good idea to remove the steering column surround & check the steering wheel buttons also. 3 wires. Will be a common wire and makes a circuit each of the other 2 depending on which switch.

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Are you referring to the engine code memory and test connectors? If so, mine are under the hood by the fuel filter and strut tower. 2 prong, no locking tab. 

 

I will be checking the switches on my next day off, after that I will check the switch wires if need be. I am suspecting the clutch switch.

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