Have 91 gmc shift to 4th gear or overdrive i lose power

SOURCE: 1995 GMC 2500 4x4 wont shift into 3rd or overdrive most of the times

i have heard that the ignition switch can be faulty and not let the full voltage thru to the electricaly controlled 4l60e trans.i have the same problem with my 95 1/2 t. i rigged a switched wire from the fuse block via a relay to the proper wire on the trans....ask a trany tech and they will know what im talking about,,,good luck

Marvin

• 85242 Answers
• Posted on Oct 31, 2008

SOURCE: transmision shifting problem

Reverse is not sycronized, this means the gears have to stop to mess and not grind, two thing cause this, being to quick to slam into reverse after clutch is depressed, a problem with the clutch.

SOURCE: 1996 GMC Jimmy will not shift into overdrive.

4th gear failure is a common problem with this transmission, assuming it is an automatic. You should have the vehicle checked for codes by a qualified repair center with the proper scan tool. Also, check fluid level and condition. More often than not, the trans loses 3rd and 4th gear, as these are working off the same set of clutches. 3-4 clutches apply in 3rd, and when the 4th shift is made the 2-4 band applies giving you overdrive. If you have no engine braking in manual 3rd, you definitely have a mechanical failure, no 4th could be an electrical, or mechanical fault.

SOURCE: 95 GMC Sierra 4L60E will not shift down to 1st or up to 4th.

no power stuck in 3rd gear electric shop unless youve burnt it up good luck...www.TransmissionGarage.com

SOURCE: My 1993 Gmc Sierra 2500 automatic first gear shifts hard also from park to drive others gears are smooth i have overdrive

The gear shift lever indicators tell you what gear you have an automatic transmission in on your vehicle. The shift solenoid tells the transmission when to shift gears and what gear to shift into. Newer model automatic transmissions have electronic shift solenoids that are activated and change gears based on the speed the vehicle is traveling. Troubleshooting either one of these transmission components is relatively easy if you know a little about automobile mechanics. With the right tools, you can determine whether the transmission shift solenoid is having a problem. Gear shift indicator problems can be determined simply by moving the gears into their designated position.
Transmission Shift Solenoid

• 1 Raise each corner of the vehicle up with the car jack and place jack stands under the frame. Make sure the car is raised high enough so you can work under the car freely.
  
• 2 Slide the drain pan under the transmission fluid drain plug. Remove the drain plug with a ratchet and socket, and let all the fluid drain out of the transmission. Remove the transmission pan bolts with a ratchet and socket. Pull the pan away from the bottom of the transmission, revealing the transmission shift solenoid.
  
• 3 Wipe off the shift solenoid with a shop towel. Disconnect one of the two plugs that attaches to the shift solenoid. Turn the knob on the volt meter to the ohms setting, so resistance can be measured. Set the volt meter on 200.
  
• 4 Take the black lead of the volt meter and touch the negative battery terminal wire. Take the red lead of volt meter and slide the tip into the terminal plug you just disconnected from the shift solenoid. Look at the reading you get on the digital display of your volt meter. Determine if the reading is between 12 and 25. Readings below 12 or above 25 tell you that the shift solenoid is not working. Reattach the plug to the shift solenoid and pull the second plug attached to the solenoid. Perform the same procedures on this plug wire. Replace the transmission shift solenoid after determining it is bad.
  

• 1 Move the gear shift into the desired gear. Look at the gear labels and the arrow, or other indicator, to see if the gear shift indicator lines up with the selected gear.
  
• 2 Move the gear lever to another gear and look to see if the indicator lines up with the selected gear. Misalignment of the arrow will tell you if there is a problem. Moving the gear shift to "neutral" but having the indicator show the transmission is in "drive" tells you the gear shift indicator is not working properly.
  
• 3 Try each gear position to determine how much misalignment is in the indicator. Slide under the car and check for a loose gear shift cable. Check all the gear shift cable connections to ensure they are all tight and are not missing. Tighten any loose gear shift cable clamps or bolts. Replace the gear shift cable if you find that this is causing the misalignment with the gear shift indicator.
  

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