My ignition switch suddenly won't turn off, and the auto gear shift selector will stick in park at the same time this happens with the switch. To top that off, the electric windows won't work. This is a 1985 Blazer S-10, 4x4, 2.8 liter. This has happened twice. First time a week ago, then ago today. Ideas on the problem? Ignition switch perhaps? Or does it go beyond that? Thanks, Dave

Your vehicle has a safety system that won't let you take it out of park unless you have the brake pedal pressed ! Your brake switch could be shorted inside causing fuse to blow !
Shift Interlock System A brake/shifter interlock mechanism prevents shifting the transmission out of the PARK position unless the brake pedal (2455) is applied. The system consists of the following components:

• an actuator activated by the key interlock assembly and brake pedal pressed input.
• necessary wiring.

The system operates as follows:

• The actuator is energized when the ignition switch is turned to RUN, locking the transmission range selector lever in the PARK position. When the brake pedal is applied and the stoplight switch (13480) is activated, the shift lock actuator is deactivated.
• The transmission range selector lever can be moved out of the PARK position.

The ignition/shifter interlock cable (3F719) locks the transmission range selector lever in the PARK position when the ignition switch is in the LOCK position. It also requires the selector lever to be in the PARK position to turn the ignition switch to the LOCK position.

Do you have column or floor shifter ?
All automatic transaxle models use an electric park lock system. Within the housing assembly, a lock cylinder is connected to an actuator which rotates and engages on the electric park lock solenoid. When the floor-shift lever is not in the park position, the actuator disengages from the electric park lock solenoid slider. This allows the lock cylinder to move to the lock position. With the shift lever in PARK and the lock cylinder in LOCK, the actuator cam is positioned against the electric park lock solenoid slider. This prevents the shift lever from shifting out of the PARK position.
The column-shift automatic transaxle model uses a flexible cable actuator instead of an electric park lock system. One end of the cable is attached to the gate assembly. The other end of the cable is attached to the column mounted housing assembly. This system functions similarly to the floor-shift ignition lock system.
The manual transaxle model uses a push button lock cylinder. A clutch start switch is used. The clutch pedal must be pressed before the engine will crank. Refer to Park Lock System Check .
CAN you turn the key on ?
The gear selector does not shift out of PARK with the brake pedal depressed and the ignition switch in RUN.
Automatic Transmission Shift Lock Control Always On with Ignition in Run
Action
Value(s)
Yes
No

1

Was the BTSI System Check performed?
--
Go to Step 2
Go to Automatic Transmission Shift Lock Control System Check

2

Is this a column shift vehicle?
--
Go to Step 3 yes
Go to Step 4 no

3

1. Move the gear selector to the PARK position.
2. Disconnect the automatic transaxle control connector
3. Turn the ignition switch to RUN.
4. Connect the test lamp between terminal B and ground.

Does the test lamp light?
--
Go to Step 4
Go to Step 8

4

1. Disconnect the brake switch connector C2.
2. Move the ignition switch to RUN.

Can you shift the transaxle out of the PARK position?
--
Go to Step 5
Go to Step 8

5

Is the brake switch adjusted properly?
--
Go to Step 6
Go to Step 7

6

Replace the brake switch.
Is the repair complete?
--
System OK
--

7

Adjust the brake switch.
Is the repair complete?
--
System OK
--

8

1. Disconnect the BTSI solenoid connector (column shift vehicles) or disconnect the automatic transaxle control connector (console shift vehicles).
2. Move the ignition switch to RUN.

Can you shift the transaxle out of the PARK position?
--
Go to Step 9
Go to Step 10

9

Repair the short to power in CKT 1135.
Is the repair complete?
--
System OK
--

10

Test for sticking or binding in the shift linkage.
Does the shift linkage stick or bind?
--
Go to Step 11
Go to Step 12

11

Repair the shift linkage.
Is the repair complete?
--
System OK
--

12

Replace the BTSI solenoid (column shift vehicles) or replace the automatic transaxle control (console shift vehicles).
Is the repair complete?
--
System OK
Go to Step 1

.
Shift Interlock System
The shift interlock system prevents a shift out of PARK unless the brake pedal is depressed. The shift interlock system has a shift lock actuator mounted on the floor shifter assembly. If the ignition switch is in the RUN position, the shift actuator will allow the shifter to be moved out of PARK only when the brake pedal is pressed.
Electroniclly controlled !

Condition Possible Sources Action

• The shift interlock system does not release or lock correctly

• Fuse in battery junction box (BJB)

• Check fuses.

• Brake pedal position (BPP) switch

• CHECK the BPP switch. REFER to Section 206-09 .

• Floor shifter wiring and/or connectors
• Transmission selector lever
• Ignition system

• Go To Pinpoint Test A .

sounds like the cable from the gear stick to the gearbox selector switch has been put on wrong ,put the car into reverse so that the reverse light is on , turn the ignition off and find the gear selector on the gearbox , pop the end of the cable off it then put the gearstick into the "R" position and refit the end of the cable back onto the selector switch , hope this helps

Electronic's . Your vehicle has a couple safety system that are computer controlled . Shift interlock won't let the gear selector move from park into a gear unless you foot is pushing on the brake pedal .Brake switch is a input to the SJB - smart junction box , ford's body control module. The SJB controls a lock solenoid that will lock the gear selector . Plus has system feature that won't let the key lock an be pulled from the ignition if not in park . Problems happen that cause these not to work . Your best bet , have a qualified repair shop check for DTC'S - diagnostic trouble codes .

Could be the brake switch or the solenoid that locks the shifter in park.
That circuit would need to be tested.

Most newer models have a safety feature called
shift interlock. This prevents the key from being turned back
to the lock position if you forget to place the gear selector in park.
Depending on the model,
If it uses a cable, it may be sticking or needs adjusting.
If it uses an electrical solenoid. may be blown fuse or park switch.
Tap, shake, and pull up on the shifter and make sure it's in park.

It did, if it is calble controlled then the cable broke from either the gear selector under the dash or on the transmission . 3 places it breaks at 1 the gear selector under the dash or the center console, connection came out or broke 2. on the transmission gear selector area there is a bushing that it connects that breaks off, 3. inside the transmission, the prawl got loose (rare but happens)

It may be a fault with the gear selector ignition isolation switch on the side of the transmission. As a safety measure the vehicle cannot be started when the gear selector is in anything other than park (maybe neutral). If the linkage between the gear selector and the selector switch on the transmission is a bit slack or the switch on the transmission is faulty the ignition might be disabled as it assumes it is actually left in gear. Check the this selector switch and the shift linkage to it. I think the fault might be easy to correct with adjustment, clean up or exchange

sounds like the cable going from the ignition switch to the gear selector assembly may be sticking. have to take cover off gear selector assembly then clean cable and connection with brake clean to clean off what ever is making it stick then spray some wd40 on it to lubricate the cable to it will slide easier