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Dave Nova
Dave Nova, GMC Technician
Category: GM
Satisfied Customers: 19452
Experience:  ASE Master Certification. GM World Class Certification
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1994 GMC Safari: ignition switch..the steering column..engine running

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1994 GMC Safari. Just did some repairs that included changing the ignition switch. I had to lower the steering column to get at it and now that its all back together I can't get the AT out of Park with the engine running. If I start it in "Neutral" then it won't shift out of neutral either. It will shift OK with the key out of "Lock" if the engine is not running. I'm also getting a Anti-lock light?? Where did that come from?
If the key is turned all the way to the RUN position, without starting the engine- will the shifter work as it is supposed to?
Customer: replied 7 years ago.
Yes, if the engine is off and the key is in the run position then you can shift OK.
With engine running and depressing the brake, do you get a click noise at the steering column?
Customer: replied 7 years ago.
With the engine running there is no click when the brake is depressed.
You should try adjusting the ignition switch first. The shift interlock may not be getting power. Check for power at the green/white wire on the shift interlock solenoid.
Customer: replied 7 years ago.
Where is the shift interlock solenoid and what does it look like? I don't know that component.

On the passenger side of the steering column.



Customer: replied 7 years ago.
I've checked for 12v at the grn/wht wire with the engine running but there was no voltage. I have a Chilton manual with some electrical diagrams but they don't include the shift interlock solenoid so I don't know how the circuit functions. Do you have a diagram you could share?
Customer: replied 7 years ago.
Thanks for the diagram, it sure will help. Where is the Brake/Shift interlock relay located? I believe I have a short in the ckt and I'm looking for it now.
The relay is located behind the drivers side of the dash. Wish I could give you a more specific location or a picture of this one. Look for the wiring going into the relay and make sure the colors match those on the diagram. This relay should click with the key on and the transmission in park.
Customer: replied 7 years ago.
The BTSI read zero ohms... dead short. Could you provide a procedure to replace it?
I am sorry, my service information does not list a replacement procedure, just the illustration I provided previously.
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Customer: replied 7 years ago.
Turns out to be an easy part to replace but hard part to find. Dealer wants $75 ... about the value of the van. But that's a different problem. I want to thank you for the good help.

As you can see I'm "accepting" at this point but I want to mention that this problem occurred right after I experienced a 'won't shift out of 1st gear problem" with the transmission. I drove home in 1st gear and then couldn't get it out of park. Do you think the two problems are related?

I was test driving it after changing the ignition switch.
The problems would not be related. The shifts are electronically actuated. If the speedometer was working, the problem with the transmission will have likely been a shift solenoid hanging up. If the transmisssion loses power completely, it defaults to 3rd gear.
Customer: replied 7 years ago.
I'm wondering if my problems are just getting started. It would appear that the shift interlock solenoid fried during my test drive after changing the ignition switch. Because it was initially working in order to do the test drive. The last thing I want is to replace the solenoid and have it fry during the next test drive.

I'd like a little more information concerning the BTSI function. Does energizing the solenoid always cause the gear shift to lock? And power to the solenoid only comes from the brake fuse? Where does the engine running or not running effect the circuit?

The btsi power does come from the brake fuse, then to the relay which is engergized when the key is on and the transmission is in park. It does not matter if the engine is running or not. That's why I was wondering if the ignition switch was correctly adjusted. The green/white wire should have power in park with the engine running or not. If it does not, check to see if the turn signals work with the engine running.

Customer: replied 7 years ago.
I can't double check it now because the solenoid is out, but I seem to remember that the transmission would shift ok with key in the run position if the engine was off and be locked in the park position if the engine was running. During all these checks the Brake fuse was blown however. What was locking it and what was unlocking it?
Without power it will lock. It needs power to unlock. You will have to wait until you can get it back together to test for power.
Customer: replied 7 years ago.
If it locks without power, how does stepping on the brake petal unlock it since that removes power? I thought.
Sorry for the misinformation, went back and looked at the schematic. Without power it unlocks. Stepping on the brake causes loss of power to the relay. The relay also opens the circuit when the transmission is in park, regardless of whether the brake pedal is depressed.
Customer: replied 7 years ago.
You mentioned checking the ignition switch adjustment... what should I look for? There does not seem to be any adjustments. I installed it with the key in the lock position?? Is there any function that I can check for to verify that it is installed correctly.

Right now I'm trying to figure out circuit operation by operating the BTSI manually. Any ideas on what to check for or verify?

Since this circuit also operates off the turn signal circuit, do the turn signals work with the engine running? This will tell you if the circuit is losing power with the engine running.
Customer: replied 7 years ago.
Yes, tlhe turns signals are working with the engine running.

I finished checking out the position for freeing the gear shift lever: I can only shift when the key is in the OFF position. The positions go ACCESS - LOCK - OFF - RUN - START. If its in the RUN position the lever is locked. Moving the key through its various positions I can watch the solenoid cable extend and retract. When the key is in OFF position I can manually push the cable back and free the lock. I can also push/pull the cable in the other key positions but the lever does not free up.
If you press the brake and pull back on the cable, will it release in the other key positions?
Customer: replied 7 years ago.
OK, I hope I can describe this w/o being too confusing.

The brake pedal position was a moot point. Since the BTSI solenoid is out all could do was monitor the input with a meter and note that with brake pedal I got 12v.

I noted two types of gear shift lock. One I could feel right in the steering wheel; a hard definite lock. The other was softer binding type stop that seemed to be down in the column.

OK. With the key in the LOCK position, and the cable pushed in, the shift had a hard lock. Pulling the cable out freed the shift. With the key in the OFF position, pulling the cable out created a hard lock. Pushing the cable back in freed the shift. With the key in the RUN position pulling the cable out created a hard lock but pushing the cable back it became a soft binding lock. I didn't do any checks with engine running.

I also noted that the cable would move in and out driven by key position. However, it never got into a position to free the shift unaided.
The solenoid is likely not be strong enough to pull the cable unaided.
Customer: replied 7 years ago.
I just reread my last posting and it was too confusing. To answer your question: "If you press the brake and pull back on the cable, will it release in the other key positions?" The answer is NO. That only worked for the LOCK key position. And that doesn't sound like proper system function does it?
Basically you should have power to the actuator any time the key is on and the transmission is not in park and the brake pedal is released. If the key is in any position other than RUN, it will have no power. If the brake pedal is depressed, there will be no power. If the transmission is shifted out of park, it will have no power. That is the way it should work.
Customer: replied 7 years ago.
Your description first says power to the actuator when the transmission is not in park and then later says power when it is in park. I think the diagram shows that you have to be in park to actuate the BSI relay which must be energized to apply power to the solenoid. ??Which would mean the gear shift would UNLOCK when you put it in park??

But if the BTSI solenoid is the only thing that determines if the gear shift lever is locked or not then by removing the solenoid and manually push/pulling the cable that attaches to it I can control the lock regardless of anything else. ?? Is there more to the locking system that I'm not aware of? Shouldn't I be able to do this?
When you are in park this energizes the relay. The relay is normally closed so when the relay is energized the contacts open.
Customer: replied 7 years ago.
I just finished checking mine and it works just the opposite (relay nornally open). With power off there is no continuity thru the Brake/Shift Interlock relay. When I turn the key on to RUN, I then get continuity. I checked this by removing the Brake fuse and reading continuity from the low side of the fuse to the green/white wire at the Brake/Transmission Shift Interlock solenoid.
You really need to have everything together and check for power at the solenoid, that would be the best way. Should only have power with the key on, in park, with the brake not applied. Sorry for the delay in responding to you, my son was ill.
Customer: replied 7 years ago.
I am very sorry to hear about your son, I hope he gets well soon. Could you provide the part number for the Brake/Transmission Shift Interlock solenoid? The vin number on the van is 1GKDM19Z9RB545603.
I am sorry, but I do not have access to part number information. If you call your local dealers parts department, they can look it up for you.
Customer: replied 7 years ago.
OK, well one last question that I hope you can find some info on. Is the locking mechanism attached to the BTSI solenoid cable the only thing that (intentionally) locks the gear shift? In other words: if I manually pull the cable that attaches to the BTSI solenoid, can I unlock the gear shift regardless of anything else?
The btsi solenoid is the only thing that intentionally locks the shifter mechanism.
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