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Old 10-10-2010, 09:42 AM
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75 GMC pickup - remove ignition switch

Truck specs: 1975 GMC K25, TH350 with a tilt wheel

The ignition switch in my '75 K25 seems to have lost its "spring", and I also can't use it to start the truck. I can turn on the truck with the ignition switch and use a remote starter switch on the solenoid and it turns over and starts fine. It might be the neutral safety switch, but it feels like there is more that is broken.

Based on the GM troubleshooting chart it looks like I need to replace the ignition switch (not the lock cylinder), and its mounted on top of the column up under the dash.

Two questions:

1- the directions state that I just need to just drop the column down, but the procedure they reference is for complete removal of the column. How much do I need to take off just to drop it down to reach the switch?

2 - Is the spring for the ignition mechanism part of the electrical switch mounted on top of the column? I always assumed the spring was right behind the lock cylinder, but never really looked. I don't want to replace the ignition switch and then find out I have to go back and remove the steering wheel to replace a lock cylinder spring before it works right.

Thanks,

Bruce

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Old 10-10-2010, 11:50 AM
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Bruce----Do you have tilt???

Everything is contained in the switch---even the return spring

Standard and tilt columns use different switches

Column must be dropped and upon switch replacement, the switch needs
to be adjusted.

If not adjusted, you might get it to start----but no ACCY
or No start and ACCY works

If you have tilt----you probably have an issue with the "rack & rod" assy
that runs from the lock cylinder to the switch.

Not a hard thing to replace--but time consuming and patience is essential.

I have yet to replace the ignition switch on my 79 with tilt.
However, about 4 turn switches, 3 rack & rods, and twice I have had to replace the pivot pins in the column.
(tilting all the time will eventually break the wires in the turn switch--
Tilt is the most used option in ALL of my cars---If I buy a car w/o tilt,
it will soon have tilt----even put tilt in my 82 D-150, required modifying the clutch pedal to clear the GM ignition switch. Must be why Dodge did not offer tilt with a manual trans.)

Drop the column a bit and apply some pressure to that rod that runs
down the column, if there is any slop or hesitation while turning the key,
the assy needs replaced-----if the rod rod moves EXACTLY as you are turning the key, replace the switch.

For a junkyard switch----it is easier to remove a switch from a Dodge truck with tilt than it is from a GM product. Same switch but it is mounted on the side of the column.
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Old 10-10-2010, 11:59 AM
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The truck does have tilt wheel. I haven't had a working accessory position for quite a while, and now I don't have a start position. It sounds like I'll just have to take it slow and careful, and it will all come apart.

I don't plan to replace it with a junkyard switch, since an OEM GM switch is only about $20, and the replacements from Advance Auto are about $15.

To "drop the column" do I just take off the bracket that holds it onto the bottom of the dash and slowly drop it down? Can I leave everything connected to the rag joint and steering box?

Thanks for the information.

Bruce
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Old 10-10-2010, 12:36 PM
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Yep----just a couple of bolts behind that lower cover.
Be careful of the PRND21 cable.
It is held to the column shift bowl with a small screw.
Release that little thing before letting the column fall.

No start AND no Accy-----I'm gonna bet the rack & rod
Not knowing exactly where you are,
Benson Chevrolet has usually given be better prices
on parts than Vara (I am closer to Vara).

But Vara is better at getting the parts in next day from Houston
or Dallas.

If the ASSY is not stocked locally----will be in Dallas or Houston
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Old 10-10-2010, 01:06 PM
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I read your reply just after I managed to break the pivot point off that the PRND21 cable runs over. I think I can superglue it back on. It would have been easier to fix if the cable had broken.

When I first turned the ignition switch I could see the actuator rod moving, but then it stopped, and it now seems disconnected from the lock cylinder. Its like the end of the rod has broken loose from the upper part of the steering wheel and the lock cylinder. I can still slide the rod back and forth manually with my fingers, but it has no "spring" to it. Is there a connector on the rod that breaks off the upper end?

I seems like time to pull the steering wheel so I can get to the place where the lock cylinder connects to the rod. The GM manual directions assume you are going to pull the entire column out, but it looks like you can get get it apart enough to reach the rod assembly without pulling the column first.
Or is there some other way to replace the rack and rod?

Also, is the part I am looking for just a rack and rod assembly for a GM tilt wheel?

I live near the middle of North San Antonio, so Benson is easy to get to, but I work at I-35 and 1604 where I'm closer to Gunn Chevrolet.

Thanks,

Bruce
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Old 10-10-2010, 03:01 PM
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You don't need to pull the column out.
You will be pulling the wheel, lock plate and turn switch (just needs to pull out and hang--not necessary to disconnect and pull completely out.

The rack and rod assy is 2 pieces.

the rod part usually gives out as the end of the rod is just pot metal--so is the rack.

Wish I had a tilt column hanging out here----I would go thru it step by step with you.

I at one time just pulled the switch out and let it hang---started it with a small screwdriver for one summer----be sure the key is in the lock and turned to run or the column will lock. (I eventually pulled the lock pin while doing a tilt repair)
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Old 10-10-2010, 07:20 PM
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I've got the steering wheel and turn signal actuator off, and I can see the top of the rod. It moves back and forth when I turn the key, so it must be broken somewhere lower.

The collar on the column (behind the steering wheel) is held in with three large phillips head screws that I can see behind the turn signal actuator. Does that collar have to come off to get the rod out? I've already got it loose, but will have to pull the turn signal wiring connector off at the bottom to get enough slack in the wiring to get the collar off.

I've also found a few broken & cracked plastic parts as I went along, so I'll try to fix it all as I put it back together. Its too bad I couldn't just find a rebuild kit that had all the parts that usually wear out.

Bruce
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