1990 buick reatta starting circuit problems

Question edited for clarity.

They all work to a similar theme. The Buick LeSabre will be close enough.

https://www.google.com/search?q=1990+Buick+Reatta.+How+to+replace+a+power+door+lock+actuator

1990 Buick Reatta Door Lock Actuator - VDO AC89312

https://www.stockwiseauto.com > ... > Door Lock Actuator
Feb 4, 2021 - Replacing the Door Lock Actuator on your 1990 Buick Reatta? The VDO AC89312 is a genuine replacement, with the fit of an Original Equipment ...
Rating: 5 · ‎1 review

Get the Best Priced Buick Reatta Door Lock Actuator - Parts ...

https://www.partsgeek.com > mmparts > buick > reatta
This part is also sometimes called Buick Reatta Power Door Actuator. We stock door lock ... Replacement Door Lock Actuator - for 1990 Buick Reatta - 839-008 ...

How about corroded battery cables (internal)

Fusible Link wiring corroded & open circuit,does
everything electrical work except the starting circuit?

Turn key & have power to starter solenoid ?
Neutral Switch !
Ignition Switch !

Tough to guess without wiring diagrams,
to see where to start testing

Can't fix what you don't know you have

I doubt it,, but I'll do some checking for you,, most master cylinders and boosters are on the firewall on the drivers side, under the hood,,

code 022 TPS ( throttle position sensor ) signal high


code 041 camshaft sensor signal

Crank sensor.

1990 Buick REATTA Recall ID from NHTSA: 90V164000 Auto Recall Date: 09/06/1990
Vehicle Component: POWER TRAIN:AUTOMATIC TRANSMISSION:LEVER AND LINKAGE:FLOOR SHIFT
Estimated Vehicles Affected: 63964
1990 BUICK REATTA Defect Summary:
TRANSAXLE SHIFT CONTROL CABLE MAY DISENGAGE FROM THE FROM THE FLOOR SHIFT CONTROL WITH LOSS OF GEAR INDICATOR REFERENCE AND SHIFT SELECTOR OPERATION.
Defect Consequence:
DRIVER WOULD NOT BE ABLE TO DETERMINE ACTUAL GEARPOSITION THE TRANSAXLE IS IN, WHICH COULD RESULT IN UNEXPECTED VEHICLE MOVEMENTAND AN ACCIDENT WITHOUT PRIOR WARNING.
Remedy:
INSTALL A TRANSAXLE SHIFT CONTROL CABLE RETAINING CLIP TO PREVENT CABLE DISENGAGEMENT.
Notes: GENERAL MOTORS CORP., 1990 Buick REATTA Recall ID from NHTSA: 91V158000 Auto Recall Date: 09/13/1991
Vehicle Component: SERVICE BRAKES, HYDRAULIC:SWITCHES:BRAKE WARNING
Estimated Vehicles Affected: 18904
1990 BUICK REATTA Defect Summary:
BRAKE INDICATOR LIGHT MAY NOT LIGHT WHEN IGNITION IS IN THE "ON" POSITION, THE PARKING BRAKE IS APPLIED, AND THE SHIFT SELECTOR IS IN THE PARK OR NEUTRAL GEAR RANGE.
Defect Consequence:
VEHICLES WOULD NOT MEET THE REQUIREMENTS OF FMVSS 101AND 105.
Remedy:
REPLACE THE PROM IN THE BODY COMPUTER MODULE TO PREVENT THIS CONDITION FROM OCCURRING.
Notes: GENERAL MOTORS CORP., 1990 Buick REATTA Recall ID from NHTSA: 90V031000 Auto Recall Date: 02/12/1990
Vehicle Component: AIR BAGS:FRONTAL:SENSOR/CONTROL MODULE
Estimated Vehicles Affected: 857
1990 BUICK REATTA Defect Summary:
THE FORWARD SENSOR FOR THE AIR BAG MAY HAVE BEEN INCORRECTLY CONSTRUCTED WITH PART OF THE WIRING HARNESS TO THE SENSOR REVERSED.
Defect Consequence:
THE REVERSAL OF THE WIRES COULD CAUSE DELAY IN THE DEPLOYMENT OF THE AIR BAG AND INCREASE THE SEVERITY OF THE OF INJURY TO AN UNBELTED DRIVER IN AN ACCIDENT.
Remedy:
REPLACE FORWARD DISCRIMINATING SENSOR AS NECESSARY.
Notes: GENERAL MOTORS CORP.

Remove and send it to model electronics to have it repaired.

it your switch, just purchase a new one

Check the terminals and make sure they are clean and tight
Check the alternator could be bad
Starter sylinoid