1993 Cruise control vacuum line

[76chevytruck]

I have 1993 1/2ton v6 TBI. hoping to get the cruise control working. replaced multifunction switch in the steering column because the wires were cut, fuse is good, now I need to know where the vacuum line connects. Does anyone have a idea? Will manifold vacuum be ok or does it need to be ported? No diagram under the hood. Thanks!

[benoit454]

my 88 has cruise and it has NO vacuum line, only a cable going to the tbi and then an electrical plugin underhood.

[ChevyTech]

As said,
No vacuum line for factory cruise on a 1993 chevy truck.

[tommie]

is it an aftermarket cruise control??

post a picture of the cruise control unit, and the switch to activate it...

[benoit454]

agrred pics would help alot.

[76chevytruck]

Give me a day to get photos. it may be a after market unit as it is not located in the same place as the one in my 88 silverado. it is activated by what looks like the factory chevy multi switch in the steering column. more to follow later. thanks

[Robert252]

Its a control box on the firewall in front of driver

[Kudzupatch]

I have a 93 we can compare it too.

[Robert252]

Hey I have a 93 Silverado ,4.3 ,manual tranny, xcab. and have checked the cruise control voltage and I have voltage w key on at F and A and also volts when I push the accelerate button and the set button but no volts for the brake pedal on or off. I just got the truck and the brake switch looks new but the clutch switch looks wore out so I bypassed it with a jumper but still no cruise control does anyone know what I can check next. Thanks

[ChevyTech]

RE: Robert252

Here are two good cruise control threads:
http://67-72chevytrucks.com/vboard/s...d.php?t=532924

http://67-72chevytrucks.com/vboard/s...d.php?t=539665

I am busy and don't know when I will get back here to the board, but I work you through this, time permitting.

Here is some 1993 Cruise control information:

Testing at the cruise unit under the hood;

Unplug the wire connector from the cruise module on the cruise unit under the hood.
Check for power on the Pink wire with black stripe (with the key on) – there should be power.
Check for power on the Gray wire (with the key on and cruise switch on) – there should be power.
Check for power on the Brown wire (not touching the brake pedal) – there should be power.
Check for power on the Brown wire (while the brake pedal is pushed) – there should be NO power.

Give me the results of these tests.

Power flow:
Gages fuse - To Cruise module & cruise switch – Pink wire with black stripe
Cruise switch – to brake switch – gray wire
(Auto transmission vehicles) Brake switch to cruise module – Brown wire
(Manual transmission vehicles) Brake switch to clutch switch on gray wire with black stripe, through the clutch switch and to the cruise module in brown wire.

Cruise switch wires colors:
Pink wire with black stripe = power in from gage fuse
Gray wire = power out of switch to brake switch and cruise module
Dark blue wire = Set & coast
Dark green wire = Resume & accelerate

Cruise module wire colors:
Pink wire with black stripe = power in from gauge fuse
Black with white stripe = Ground
Brown wire = power back from brake switch (and clutch on manual transmission vehicles)
Dark blue wire = Set & coast - signal from cruise switch
Dark green wire = Resume & accelerate - signal from cruise switch
Gray wire = power from cruise switch
White wire = to PCM – (TCM on diesel engines)
Red with white stripe = Vehicle speed signal from DRAC module

[Robert252]

Thank you, I will start the tests this weekend and get back with you thanks again

[Nitis]

On my 93 I know I wound up replacing my brake light switch as it is tied in its a cheap part and worth a shot.

I followed a similar sequence that chevy tech posted

[c10sport]

Great thread. I've replaced the cruise module, the brake switch, turn signal stalk checked the redundant brake switch, and checked every inch of wiring in my '89 and still doesn't work.

[Robert252]

Originally Posted by ChevyTech

RE: Robert252

Here are two good cruise control threads:
http://67-72chevytrucks.com/vboard/s...d.php?t=532924

http://67-72chevytrucks.com/vboard/s...d.php?t=539665

I am busy and don't know when I will get back here to the board, but I work you through this, time permitting.

Here is some 1993 Cruise control information:

Testing at the cruise unit under the hood;

Unplug the wire connector from the cruise module on the cruise unit under the hood.
Check for power on the Pink wire with black stripe (with the key on) – there should be power.
Check for power on the Gray wire (with the key on and cruise switch on) – there should be power.
Check for power on the Brown wire (not touching the brake pedal) – there should be power.
Check for power on the Brown wire (while the brake pedal is pushed) – there should be NO power.

Give me the results of these tests.

Power flow:
Gages fuse - To Cruise module & cruise switch – Pink wire with black stripe
Cruise switch – to brake switch – gray wire
(Auto transmission vehicles) Brake switch to cruise module – Brown wire
(Manual transmission vehicles) Brake switch to clutch switch on gray wire with black stripe, through the clutch switch and to the cruise module in brown wire.

Cruise switch wires colors:
Pink wire with black stripe = power in from gage fuse
Gray wire = power out of switch to brake switch and cruise module
Dark blue wire = Set & coast
Dark green wire = Resume & accelerate

Cruise module wire colors:
Pink wire with black stripe = power in from gauge fuse
Black with white stripe = Ground
Brown wire = power back from brake switch (and clutch on manual transmission vehicles)
Dark blue wire = Set & coast - signal from cruise switch
Dark green wire = Resume & accelerate - signal from cruise switch
Gray wire = power from cruise switch
White wire = to PCM – (TCM on diesel engines)
Red with white stripe = Vehicle speed signal from DRAC module

Ok I checked for voltage on the pink = Have PWR
Checked for voltage on the grey wire = have PWR
Checked for voltage on the brown wire with brake not pushed = NO POWER.

But I do have a brake warning light that comes on when I get up to 35 mph. but it is not as bright as when I have the park brake on.

[ChevyTech]

Originally Posted by Robert252

... Checked for voltage on the brown wire with brake not pushed = NO POWER.

The most probable cause is the brake switch.
The brake switch is a high failure parts on these trucks.
If the switch was out of adjustment is could cause the problem.

For C/K trucks 1988 to 1993

Here is how the switch is adjusted:
On the curved side of the switch, which is pointing down and somewhat towards the front of the vehicle when installed, the end of a lever protrudes slightly out of a slot.
While holding the brake pedal down a little ways, slide the lever that protrudes from the slot toward the driver’s seat.
Let go of the lever, and then return the brake pedal to its fully released position, and the switch should self adjust.

Brake Switch mounting – Installing:
The body of the brake switch should not move with the pedal at all. Remove the switch and install it again. When you have the switch removed look at the side of the switch that would be towards the parking brake pedal if the switch were still installed. There is a protrusion on the switch that must slide into an opening where the switch mounts. Somewhat like a big square lug into a slot.

Originally Posted by Robert252

But I do have a brake warning light that comes on when I get up to 35 mph. but it is not as bright as when I have the park brake on.

The RWAL (Rear Wheel Anti Lock) is setting a code 10.

Code 10 indicates problem with the brake switch at the brake pedal or the circuit for it.
It is common for the brake switch to go bad on these trucks.
Check and see if your brake lights work, but even if the brake lights work ok there could still be a problem with the brake switch because it has multiple contacts for multiple circuits through it.
The self test for code 10 happens when the vehicle reaches 35 MPH.

[ChevyTech]

Originally Posted by c10sport

Great thread. I've replaced the cruise module, the brake switch, turn signal stalk checked the redundant brake switch, and checked every inch of wiring in my '89 and still doesn't work.

Check the voltages out at the module and let me know what you find.

Below are the wire colors for a 1988 which should give you enought to figure out if your does not match the 1993 colors.

Cruise module wire colors 1988

Pink = Power from Ignition
Brown = from brake switch/ clutch switch (power when not touching pedals)
Gray = Power when cruise switch on
Dark blue = Set switch
Dark green = Resume/accel
brown w/ white stripe = speed signal input
black w/ white stripe = Ground

[Robert252]

Originally Posted by ChevyTech

The most probable cause is the brake switch.
The brake switch is a high failure parts on these trucks.
If the switch was out of adjustment is could cause the problem.

For C/K trucks 1988 to 1993

Here is how the switch is adjusted:
On the curved side of the switch, which is pointing down and somewhat towards the front of the vehicle when installed, the end of a lever protrudes slightly out of a slot.
While holding the brake pedal down a little ways, slide the lever that protrudes from the slot toward the driver’s seat.
Let go of the lever, and then return the brake pedal to its fully released position, and the switch should self adjust.

Brake Switch mounting – Installing:
The body of the brake switch should not move with the pedal at all. Remove the switch and install it again. When you have the switch removed look at the side of the switch that would be towards the parking brake pedal if the switch were still installed. There is a protrusion on the switch that must slide into an opening where the switch mounts. Somewhat like a big square lug into a slot.


The RWAL (Rear Wheel Anti Lock) is setting a code 10.

Code 10 indicates problem with the brake switch at the brake pedal or the circuit for it.
It is common for the brake switch to go bad on these trucks.
Check and see if your brake lights work, but even if the brake lights work ok there could still be a problem with the brake switch because it has multiple contacts for multiple circuits through it.
The self test for code 10 happens when the vehicle reaches 35 MPH.

Thanks for the info I will adjust the switch. The switch that is in there looks pretty new.
Are you saying that if the switch is out of adjustment the power wont go to the brown wire? The brake lights work ok.

[c10sport]

Here's from another thread. GMT400 cruise control manual.

GM STG 1992-1998_CK_Electro_Motor_Cruise_Control

[ChevyTech]

Originally Posted by Robert252

Thanks for the info I will adjust the switch. The switch that is in there looks pretty new.
Are you saying that if the switch is out of adjustment the power wont go to the brown wire? The brake lights work ok.

You're welcome.

If the brake lights work, then the switch should be in adjustment.

It is easy to adjust the switch, so it is worth a try, but there is a good chance the brake switch has failed.

Remember there are multiple circuits through the brake switch, and it is a weak point.

Also make sure power is going in the brake switch on the gray wire, with the cruise turned on.

I would test the brown wire coming out of the brake switch for power, too see if the switch is bad before going to buy a new switch.

[Robert252]

I have 2 grey wires coming from the clutch switch to the brake switch.
I have one pink one purple one orange and one white coming from the brake switch. Which go toward the fire wall.


Also I have a bigger gage black wire coming from the cruise switch to a terminal thing that I have sent as an attachment that has a green, blue, grey and pink wires coming out of it .

[ChevyTech]

Originally Posted by Robert252

I have 2 grey wires coming from the clutch switch to the brake switch.
I have one pink one purple one orange and one white coming from the brake switch. Which go toward the fire wall.


Also I have a bigger gage black wire coming from the cruise switch to a terminal thing that I have sent as an attachment that has a green, blue, grey and pink wires coming out of it .

That does not look like General Motors switches.

It must have aftermarket cruise control that someone added after it was built.

Post a photo of the unit under the hood.

[Robert252]

Hey Chevy tech ! AKA Genus!!

I used your info you provided for me and found the problem in the clutch switch. Now I have CRUISE Thank you so much. I am very thankful for your help.

THANKS AGAIN.

[ChevyTech]

You're welcome!

Glad to hear you got it fixed.