Overdrive not working

Tiny
FIXITMR
  • MECHANIC
  • 1995 PONTIAC TRANSPORT
  • 3.8L
  • V6
  • 2WD
  • AUTOMATIC
  • 225,000 MILES
When I bought this and drove it home to do repairs I thought OD was working but when I got it on the road after repairs it is not. The books it is 4L60E but I noticed a vac line to a cylindrical attachment on front of trans I do know it is a 3 spd with OD since column says 1 2 D circleD. There is also and electrical connector close to vac attachment. 1 2 3 reverse seem to work fine although the are snppy when cold and a little less crisp when warm.
Wednesday, April 13th, 2016 AT 2:08 PM

17 Replies

Tiny
FIXITMR
  • MECHANIC
  • 9,990 POSTS
The speedometer and tachometer are working fine the SES light is on so is ABS the vehicle has a OBI connector under dash but the pinout is different from say 94 on down? 1 auto store I tried a read said could not read it. I'm wondering if a rewire or plug change could solve this issue?
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Wednesday, April 13th, 2016 AT 7:18 PM
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
You may have OBD1.5 which was only year they made it. You'll have to find a local pro to read this IF he has an adapter or a dealer with a tech 2 it is not an OBD1 connector OBD1 has 12 slots OBD1.5 has 14 and OBD2 has 16
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Thursday, April 14th, 2016 AT 6:27 AM
Tiny
FIXITMR
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It LOOKS like an OBI connector and it does fit the external shape but yah I am surprised auto stores dont seem to have it in their arsenal!
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Sunday, April 17th, 2016 AT 6:55 PM
Tiny
FIXITMR
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Can you supply a pinout for the trans! Still not sure what trans is in it could be 4T60 or 4T60E I know it has vac pressure modulation unit. And plug looks like 4T60(E)
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Sunday, April 17th, 2016 AT 6:58 PM
Tiny
FIXITMR
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Gettin hot out need the AC!
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Sunday, April 17th, 2016 AT 6:58 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 52,235 POSTS
Here is some info that might help, and a picture of the plug.

https://www.2carpros.com/articles/buick-cadillac-chevy-gmc-oldsmobile-pontiac-gm-1983-1995-obd1-code-definitions-and-retrieval-method

Let us know what you find
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Sunday, April 17th, 2016 AT 7:07 PM
Tiny
FIXITMR
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Ok heres more info door sticker says manufactured 09-94. The OB plug is 12 pin style like previous yrs and it has 3 live pins in holes A M and K which is different from standard OBI
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Sunday, April 17th, 2016 AT 9:07 PM
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
You need someone with atech 1 or 2 with the adapter for that to pull codes. There are two different transmissions in this a 3t40 or a 4t60e. See pic for id tag. Make sure there are no vacuum leaks etc.
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Monday, April 18th, 2016 AT 7:24 AM
Tiny
FIXITMR
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I cant easily get to that ident plate or surface. There is a barcode sticker on side pan I can somewhat read from under hood. I see a large number 5 and large letters K U
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Monday, April 18th, 2016 AT 10:42 AM
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
The tag on the trans ides it the one you are talking about is for plant build
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Monday, April 18th, 2016 AT 11:57 AM
Tiny
FIXITMR
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Ok did google search on pics its not a 3t40 so it must be the 4t60 the side pan looks right besides other indicators. Can you supply a electric connector pinout/wiring diagram?
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Monday, April 18th, 2016 AT 2:57 PM
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
If you don't scan for codes you don't know where you are.
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Monday, April 18th, 2016 AT 3:33 PM
Tiny
FIXITMR
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On my older APV van it a simpler setup maybe just a wire to TCC solenoid that when energized produced lockup. Ths trans I see has something called PWM TCC along with TCC solenoids. A complication? Although I recall from reading some crossover work that they ignored wiring the PWM with no ill effects. Im assuming the input is a +12v? Dont know how soon I can get a scan or where yet.
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Monday, April 18th, 2016 AT 4:46 PM
Tiny
FIXITMR
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This page has good info on the 4t60e transmission electrics

http://www.automotiveforums.com/t961954-transmission_problem_tcc_.html

i guess the solenoids are all hot until they are grounded by computer. also says TCC should work fulltime unless commanded not to. always on, commanded off which is the opposite of my old van always off commanded on.
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Monday, April 18th, 2016 AT 5:00 PM
Tiny
FIXITMR
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Just to clarify always on meant always getting 12v and using ground as the control. I know, even I got confused! So to test it I just have to check for ground signal if there is 1 then solenoid itself may be problem. Hopefully code read will also help if I can get 1 soon.
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Monday, April 18th, 2016 AT 5:08 PM
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
I have no further comments you are asking for trouble if you hot wire the tcc besides it's probably teh clutch in torque converter that is shot or a pressure problem. If you don't get it scanned you don't know where you are. I am done with this matter
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Tuesday, April 19th, 2016 AT 5:57 AM
Tiny
FIXITMR
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Ok thanks. Yah i'm not gonna play with it its not as easy as the old 1's funny thing is I unplugged trans to get wire colors and after replugging it shifts harder! Didn't look dirty inside?
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Tuesday, April 19th, 2016 AT 2:55 PM

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