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95 tbi idles great, does like the switch turned off as soon as shifted out of park.

shady

shady

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My buddy's 95 k2500 with 5.7 tbi and auto is having issues.
It will start and run fine, revs up quick and decent, then about 1 out of 3-4 times it's shifted out of park, it will die before the gear lever is even fully to reverse. :dunno:

When he told me about it over the phone I assumed vac leak. Then when I seen it happen it's like the switch is just turned off.
I can't think of anything that has to do with the gear shifter that would do this.
Except maybe an electrical short in the column or something.


Anyone ever had a similar deal with a gmt400?
I was kind of hoping it's a known problem or something..... Hey look here, type of thing lol.

I'm guessing we're in for a long diagnose though.
 
I watched that at the key and that's not moving.

I'm not sure what the insides of a gmt400 column looks like though. Kind of wondered if something was disturbing the rod going to the switch if it has one like a square.
 
It's not really a stall. More like electrical. Doesn't so much die, more like shutoff.

I haven't been able to look at it for a couple days.
Probably get back to it tomorrow.
I keep leaning to either a short in the switch that tells the computer what gear it's in. Or something in the column it's self. It's got around 225k I believe and spent the last 5 years parked un-driven next to a corn field until this spring. Could be chewed wires or something.

The last time I played with it, I started it, and put it in reverse -park-reverse-park-reverse-park. The third time, about halfway between park and reverse it tried to shutoff them made contact again or whatever and just kept running.
If it actually stays running until your in drive, you can drive all over and it will run.

Some weird chits going on with it.

I had about a 2% hope when I posted this that someone would jump on and say " ah that's just this switch, gmt400s do it all the time". Or some chit. Long shot lol.
 
when you put in gear the whole engine moves, might be bad loom at back of engine and rubbing/shorting out on fire wall. Esp if has sat for 5 years rodent damage is my first suspect
 
I disconnected the shift indicator switch and neutral safety switch. They looked decent, but had been dowsed in coolant from a bad hose we recently fixed. Cleaned them anyway and hooked them back up.

At the same time we fixed an obviously long time broken frame to body ground. Then tied that ground to the engine just because.

It started fine and we put it in and out of gear about 30 times lol. It never once tried to die. Soo... :dunno:
He's going to try it out and see what happens.
 
I once had a 4x4 shift control (GMT800) fall into some coolant. I dried it out and it didn't work. After taking it apart and cleaning under the contacts, it worked fine (come to think of it, that's been working for probably 10 years now). So the glycol does have an effect on the conductivity.
 
He had the weird quick connect fitting that goes from the back of the I take to the heater core go bad. Puking coolant all down the back of the block and trans. Got that fixed and this started
 
Well, chit. Now I'm real stumped.

Air cleaner off, engine turning over, no fuel coming out of the injectors, won't pop on ether. Soo....
Something is killing the power for that crap or....?
 
We replaced the module inside it, and the pickup looks good.:dunno:

We also loosened the incoming gas line and hit the key. Gas sprayed out .

I was thinking injectors themselves , except it won't run on ether, or dribbling gas down the tbi.
More I think about it I keep coming back to ignition switch, but I'm running down the list of other things that might affect gas and spark.

Thought oil pressure switch but I believe it just cuts the fuel pump out.
 
Doesn’t a 95 have that module that has the dielectric glue or whatever underneath it, or is that the one you replaced? (I’m still living in the 80s with carbs so excuse my ignorance)
 
the weirdest part is that every now and then it'll start and run great:doah:.
For a bit lol.
 
yeah the pick up coil is still suspect in my mind. ohm check it while moving the wires
 
Try starting it Neutral..then bump it in drive.

Try the above on the lift... Curious about the electric locked Converter
Being electronic.. plug it into a good scanner / computer, or Scope.

Use due diligence looking for chewed up / damaged wires
 
Turns over great. Cranks like a champ. Just has no spark, and fuel coming out of the injectors.

And it's electronic but not ODB2. My scanner won't hook to it.

Haven't looked at it in a few days, doing a rust fix job on the neighbors caddy.
We have to check the pickup coil in the dizzy yet. And I was going to see if I can un plug the ignition switch down under the dash and check for continuity in all the right places..
As soon as I figure out what the right places are lol.
I have a bunch of schematics that someone linked in my bass burb thread. I just haven't dug into them yet.


I just tried it in neutral, same deal.
 
Ok...it has OBD1 .. they could be plugged in for diagnostics...... Either a hand held device or Shop Scope.

Have you checked for power at the distributor?

Fuses?
Fuseable links?
 
All fuses are good. Fusabe links..... Couldn't tell you were any of them are.

I think my scanner deal can do odb1, but I'll have to see if there's a cable I can buy or something.
 
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