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Ivan
Ivan, ASE Certified Master Technician
Category: Chevy
Satisfied Customers: 4870
Experience:  ASE Master Tech. 20+ years experience. 9 years self employed. Expert on AUTOLAB Radio Show
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1994 chevy s10 blazer: tranny not shifting and spedo dont work..vss

Customer Question

I have a 1994 chevy s10 blazer 4.3 vortec. tranny not shifting and spedo dont work. replaced vss and no change. i think its the buffer but have no idea of its location. where is it located and if thats not the problem any other ideas what i could be.
Submitted: 4 years ago.
Category: Chevy
Expert:  Ivan replied 4 years ago.

HelloCustomer yes it very well could be the buffer. Since you replaced the VSS with no success, the buffer would be exactly where I would go next. Here is it's location and let me know if you need additional help after tackling it.

 

Your JA Expert,

Ivan

 

graphic

Ivan, ASE Certified Master Technician
Category: Chevy
Satisfied Customers: 4870
Experience: ASE Master Tech. 20+ years experience. 9 years self employed. Expert on AUTOLAB Radio Show
Ivan and 7 other Chevy Specialists are ready to help you
Customer: replied 4 years ago.
Thanks very much ill give that a try tomorow after work. then ill either accept or throw in more info
Expert:  Ivan replied 4 years ago.
No problem, I'm with you if you need me.
Customer: replied 4 years ago.
so i replaced the vss buffer and the spedo works. Thanks alot for the help it was a snap now that i knew where it was. But now my tranny is not shifting any ideas to what this could be.
Expert:  Ivan replied 4 years ago.
You may have codes set in memory that is blocking the computer from letting the transmission from moving out of a limp mode. Try disconnecting the battery for 30 minutes. Reconnect and see if the transmission starts shifting. Let me know what happens.
Customer: replied 4 years ago.
That did not work left the battery unhooked overnight. The tranny still does not shift. if u r wondering i have a 1992 jimmy i am snagging parts from.
Expert:  Ivan replied 4 years ago.
Your truck should have a 4L60E. That is an electronic trans with no shift linkage. If it's not shifting, there must be codes stored in memory. See if you can check codes in the transmission. We need to see if we can get communication with the transmission. Let me know what you find.
Customer: replied 4 years ago.

How would i connect to the trasmission is there a special way to do so. to pull the cel coded i used a jumper wire. Would a code scanner with the obd on 12 pin adapter be able too.

Expert:  Ivan replied 4 years ago.
Sorry about the delay. A code scanner like that would, but only if it can access transmission data. When this truck is running, does the check engine light stay on and does it light when you turn the key on without starting the engine? Also when you drive it, does it feel like it's in first gear or third gear?
Customer: replied 4 years ago.
The cel light does not stay on when running. It does light when turn key. When first ran after cold it is in first and at redline will shift to 2nd.
Expert:  Ivan replied 4 years ago.
Let's check you throttle positioning sensor. That is a deciding factor in trans operation. Make sure with the key on and engine off, that sensor is .45-.55 v with closed throttle. Open throttle slowly and see if voltage moves smoothly to 4.5 volts or higher with no drop outs. Let me know if that's OK, then I'm going to try to guide you to see if we have power making it to the transmission components. It is definitely speedometer based, so I'm keeping that in mind with your previous issues. Did you have this trans issue before when the speedometer was inoperative?
Customer: replied 4 years ago.
I do not know. I bought the car this way. It needed tires. And brakes. Started driving and noticed no spedo no shift
Expert:  Ivan replied 4 years ago.
Ok, let's first start with the TPS. The blue wire at the TPS is the signal wire where you will test. Let me know and then we'll proceed to the trans.
Customer: replied 4 years ago.
Ok it goes from .5 too 4.5. So that's good now what
Expert:  Ivan replied 4 years ago.
In the fuse box, find the fuse labeled GAGES. It's a 20 amp fuse, see if that fuse has power on both sides of the fuse with the key on.
Customer: replied 4 years ago.
There is only power on one side
Expert:  Ivan replied 4 years ago.
Yay, replace that fuse, your trans should wake up.
Customer: replied 4 years ago.
My bad. I took the fuse out I thought we were looking for a short. Its good fuse. Sry so what's the next step
Expert:  Ivan replied 4 years ago.

Oh, you had my hopes up. I'm supplying you a wiring diagram for the trans. Print it so we can use it for reference. At the large connector on the trans. Unplug it and see if you have 12 volts on the pink wire.

 

graphic

Customer: replied 4 years ago.
Yep 12 volts
Expert:  Ivan replied 4 years ago.

Look at the diagram, we are going to test each shift solenoid to see if they exhibit and audible click. Look at the diagram with the shift solenoids. All the solenoids have 12 volts flowing through them with the key on always. The computer grounds them to activate them. I want you to find the wire that is not common to all the solenoids and momentarily supply ground to the wire and listen for a noise from the trans pan area. For the 1-2 shift solenoid, that will be the light green wire, for the 2-3 shift solenoid, that will be the yellow w/black wire and the 3-2 solenoid will be the white wire. Now you can do this at the computer or the harness at the trans, which ever is easier. I will attach a pinout of the computer if you choose to do it there.

 

graphicgraphic

Customer: replied 4 years ago.
ok were going to do that. If u get us working ur gonna have a decent bonus. Were doing it now


Expert:  Ivan replied 4 years ago.
If you reply and I don't respond, I've got to step out for a birthday party. I'll check as soon as I get home
Customer: replied 4 years ago.
Neither soleboid shifts. I'm using a multi meter I get 12 volts through it but no clicks
Customer: replied 4 years ago.
Nevermind. I used a piece wire and they all 3 click.
Expert:  Ivan replied 4 years ago.
Ok, I'll get back to you with a couple of other things. After that we may be looking at a transmission. I'm not home yet, but I'll get you a couple of other thoughts as soon as I get home.
Customer: replied 4 years ago.
ok we have already entertained the thoughts of replacing the transmission. We do have the spare. Would it be something worth while taking to the dealer and checking for stored codes.
Expert:  Ivan replied 4 years ago.

Here is what I'd like you to do next. Those same three wires that you just tested, hook a volt meter to each one, one at a time. You should have 12 volts on that wire if the solenoid is not turn on by the computer. I want you to start the truck and see what you have on those 3 wires in park, neutral, drive, 3, 2, 1, then what are they while you are in 1st gear and what are they when it shifts into 2nd. Give it to me in the best, XXXXX XXXXX way you can and I'll cross them over to see what the computer is doing.

Customer: replied 4 years ago.
Ill get it tom afternoon sometime thanx a million

Expert:  Ivan replied 4 years ago.
You are welcome.
Customer: replied 4 years ago.
Is there a easy way to tap the wiring i usually use a needle then attatch the leads. its just hard to drive while trying to keep the leads in
Expert:  Ivan replied 4 years ago.
Yes, use simple straight pins and you can pierce the wire, then clip the lead to the pin. That won't hurt the truck, since it's a minimal hole.
Customer: replied 4 years ago.
ok 1/2 solenoid has 12v in 2nd only, the 2/3 solenoid had 0 the whole time, the 3/2 had 12v in P R and 1. That was while sitting still. now while driving the 1/2 had 12v when it shifted to 2nd, the 2/3 never had voltage and the 3/2 had 12v in 1st. hope this helps
Customer: replied 4 years ago.

MY BAD realized had bad lead the 3/2 info changed. everything was the same except for 3/2 shift.

 

 

 

ok 1/2 solenoid has 12v in 2nd only, the 2/3 solenoid had 0 the whole time, the 3/2 had 12v in P R N OD D and 1. That was while sitting still. now while driving the 1/2 had 12v when it shifted to 2nd, the 2/3 never had voltage and the 3/2 had 12v in 1st. hope this helps

Expert:  Ivan replied 4 years ago.
Ok, I'm going to decipher the data and I'll get back to you to see as soon as i have a feel.
Expert:  Ivan replied 4 years ago.
Ok, sorry about the delay. After a bunch of analyzing, I feel you have a mechanical issue with the trans. Install that spare trans you have and let's see if that puts you back on track. Make sure you flush the cooling lines and the cooler to make sure any contaminants don't hurt the replacement trans.
Customer: replied 4 years ago.
thanks well change it out this weekend.
Customer: replied 4 years ago.
Hey. What tranny is in a 1992 gmc jimmy. 4.3
Expert:  Ivan replied 4 years ago.

A 92 4.3 has a 4L60 trans and the 94 has a 4L60E. They are not interchangeable. The 92 has a TV cable going from the trans to the throttlebody, the 4L60E has no such cable.

Customer: replied 4 years ago.
i noticed thanks for the anser. another ? will a 4l60e out of a 1996 suburban work?
Expert:  Ivan replied 4 years ago.
It may, but I can't vouch for tailshaft lengths and spline count on the rear shaft. Gear ratios may be different from the V8 to the V6 as well
Customer: replied 4 years ago.
alright sry bout the long delay replaed tranny and same problems any ideas of what it could be
Expert:  Ivan replied 4 years ago.

Ok, why do things need to be so difficult sometimes. Let's try this. With the connector at the trans connected, let me know the voltages on all the wires. Give me colors with voltages with the key on. Also unplug that connector and do the same. Let me know what you have and I will compare your results with some diagrams and see what we find.

 

Ivan

Customer: replied 4 years ago.
ok its at the tranny shop right now. theres suposeed to know today they said it might need to come out. So if they say that im bringing it back home. is it possible a solenoid is bad even owe when grounded they click. isnt there supossed to be a certain resistance on them?
Expert:  Ivan replied 4 years ago.
What we are going to do is check to see if the computer is activating the solenoids or even being connected to the trans or seeing the data from the trans. If both transmissions are doing the same thing, maybe we have a wiring issue between the trans and the computer. We will focus on that possibility heavily.
Customer: replied 4 years ago.
Ok the tranny shop said it is internal and the comp checks out and so does wiring. We r going to try another tranny thanks for the help. Ill keep in touch.
Expert:  Ivan replied 4 years ago.
Ok, that sounds like at least we are on the right track. Keep me in the loop. Good luck.
Customer: replied 4 years ago.
Ok sorry this has been so long been to like 5 transmission shops all say the scanner wont communicate with the computer. Is there a separate computer for the transmission or just one computer for the whole car. As i recall a heater core was donte just before i received the vehicle so i think maby they spilled coolant on the computer behind the dash on the pass side and shorted something internally. Thank you and again sry it took so long to get back to u.
Expert:  Ivan replied 4 years ago.
The PCM controls the engine and transmission. There is no external transmission control module. It is very possible that the transmission portion of the PCM has failed and if it can't be communicated with, its very possible that it is not awake to control the shift solenoids.

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