1988 GMC Suburban cruise control not working after engine replacement, what should I look for?

Question edited for clarity.
Question moved to model category.

3: 1988-95 5.0L, 5.7L and 7.4L Engines Firing Order: 1-8-4-3-6-5-7-2 Distributor Rotation: Clockwise.

GM Full-Size Trucks 1988-1998 Firing Orders Repair Guide

Diagrams

https://www.google.com/search?q=1995+GMC+5.7l.+C1500+SLE.+Suburban.+Firing+order

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CONTROL MODULE-IGNITION

1992 GMC Truck C1500 1/2ton Sub 2WD 5.7L TBI 8cyl

The Control Module-Ignition is located: Under hood, center, rear engine area, mounted in distributor

If the switch is replaced,then it can be wiring issue or faulty cruise control board.But as the switch is replaced,get the voltage at the switch tested to confirm the switch is actually receiving voltage.If no voltage received at switch power supply wire then ,apply external 12 volt power to the cruise control switch wire and then see if cruise control comes ON.If yes,then you know wiring is issue.
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On this case, to troubleshoot this problem, there are solved help links. Click the link directly and refer the details to solve this problem yourself, with help of diagrams: ------

Ford ranger cruise control not working? http://technoanswers.blogspot.in/2012/02/ford-ranger-cruise-control-not-working.html

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Horn and Cruise control quit working?

http://howtobyme.blogspot.com/2011/11/horn-and-cruise-control-quit-working.html

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Horn and cruise control not working on Plymouth Grand Voyager?

http://howtobyme.blogspot.com/2011/11/horn-and-cruise-control-not-working-on.html

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Horn and Cruise control quit working on 2003 Jaguar S-Type?

http://howtobyme.blogspot.com/2011/11/horn-and-cruise-control-quit-working-on.html

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Cruise Control stops working, Excessive cranks to start the engine and RPM goes max 2500

http://whoisbyme.blogspot.in/2012/07/cruise-control-stops-workingexcessive.html

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Cruise control stop working on 1994 Ford ranger?

http://technoanswers.blogspot.in/2012/02/cruise-control-stop-working-on-1994.html

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Cruise control not working?

http://schematicsdiagram.blogspot.com/2011/12/cruise-control-not-working.html

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1996 Ford Explorer: Cruise Control Wiring Diagram?

http://schematicsdiagram.blogspot.in/2012/06/1996-ford-explorer-cruise-control.html

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These will help.

Thanks.

send issue to magicmechanic in orlando--hes a specialist and will reply

No kidding. What kind of help?

how many switches on teh brake pedal ,bet their is more than one

Cruise control is suppose to cancel when brakes are applied.

Did you try just changing the bulbs?

If its not the bulbs I would have to say check the brake light switch at the pedal, it is a different switch than the cruise control cut out switch.

Btw, I’m available to help over the phone in case u need at https://www.6ya.com/expert/sean_54c3a3dc48a7773c

Check to see if the vacuum line leading to the cruise control under the hood has come loose.

I had a similar problem with my 99 Suburban. After not being able to solve the problem for about six months, my headlamps stopped working on the low beams. This led my mechanic to change the multi-function switch on the steering column (turn signal/cruise control switch/high beams) When he did this he discovered that the wire terminals at the switch had gotten hot enough to melt a little, this allowed the ground terminal to slip out of the connector. Once replaced, the cruise control miraculously started working again. I have had no problems with it for the last four years. The local GM dealer told me later that they had quite a few trucks with the same problem and it typically started with customers noticing that their cruise control stopped working. Give this a try!