Driving your Hummer can be dangerous if it doesn’t shift out of a certain gear. Now, you’re wondering why this problem started. Also, what’s the best way to fix it? We researched these concerns for your convenience, and here’s the information we found.
A Hummer that refuses to shift gears might be because of an electronic glitch, broken shifter cable, or low transmission fluid. Make sure to search for and verify the source of the problem. Then, you can use the appropriate DIY solution based on the results of your troubleshooting.
Keep reading as we talk about the possible reasons why your Hummer’s transmission fails to shift gears when needed. Read through each section as we highlighted a possible solution that may help fix your vehicle’s transmission system.
4 Reasons Why Hummer Fails To Go Into Gear (And Their Possible Fixes)
A software error may prevent the Hummer’s transmission from changing gears, despite moving the shifter to a different setting. It's important to note that this underlying issue may happen at any time, regardless of the vehicle's current state. Park it in a safe location immediately if you're driving and the shifter fails to respond to your commands.
How To Fix
Resetting the Hummer’s electronics may help restore the transmission’s normal functions. You might need significant automotive expertise or special tools for this job.
Follow these general steps to reset your Hummer’s electronics, which may include its transmission system:
- Disengage the engine and ensure it’s off. Engage the emergency, hand, or parking brake afterward.
- Open the hood once it’s safe to touch.
- Disconnect the battery cables from their terminals, starting with the negative wire.
- Wait a few minutes before reattaching the cables, starting with the positive wire.
- Turn on the Hummer’s engine and check if the shifter now registers the gear changes.
Broken Shifter Cable
If disconnecting and reattaching the battery’s cables didn’t work, perhaps the culprit to your Hummer’s failure to change gears is a broken shifter cable. This underlying problem may likely appear because of frequent rough gear shifting.
How To Fix
Replacing the broken gear shifter cable is typically the best option to recover the shifter and transmission system’s proper functionality. Unlike the previous technique, this replacement procedure often demands adequate automotive knowledge and experience.
If you believe you have the confidence to proceed with this task, follow these general steps:
What You’ll Need
- Floor jack
- Wheel chocks
- Ratchet and socket
- Panel remover
- Replacement shifter cable
- Disengage the Hummer’s engine and engage its emergency, hand, or parking brake.
- Raise the front of the vehicle with a floor jack.
- Chock the grounded wheels to prevent the vehicle from rolling or making unwanted movements.
- Go underneath the Hummer and locate the shifter cable.
- Remove the fasteners underneath the vehicle securing the broken shifter cable assembly.
- Pull out the trim surrounding the gear shifter.
- Enter the Hummer’s cabin and remove the rest of the offending shifter cable from the inside.
- Attach the gear shifter cable to the correct terminals.
- Route the cable through the correct holes so that the other end appears underneath the Hummer.
- Connect the other end of the shifter cable to the appropriate terminal and secure the assembly.
- Turn on the Hummer’s engine and test if the new shifter cable works as intended.
Tip: You can also replace the gear shifter's cable bushing in this procedure. This additional step is ideal if that component is about to wear out or is already broken.
Check out this replacement Hummer H2 shift cable bushing on Amazon.
You can also watch the video below if you need a visual guide for this procedure. Also, you might need to turn the volume up or wear headphones to listen to the person talking in the video:
Low Transmission Fluid
Like most vehicles, Hummers depend on transmission fluid to ensure their gear-shifting capabilities work correctly. Take note that you should refill your Hummer’s transmission fluid at least once every 90,000 miles. Otherwise, the vehicle might experience issues like its failure to go into gear.
Other signs of low transmission fluid to watch out for are:
- Gear slips
- A clunking or grinding racket during attempted gear shifts
- An unknown burning smell in the cabin
- Poor transmission performance
- Persistent check engine warning light
- Noticeable indication of fluid leak underneath the Hummer, particularly when parked
How To Fix
Refilling your Hummer’s transmission fluid reserves may help solve the gear shift failure. Be careful not to mix transmission fluids in your vehicle. Otherwise, it increases the likelihood of bringing additional harm to the vehicle.
After checking and purchasing the correct transmission fluid for your specific Hummer model, follow these steps:
What You’ll Need
- Drain pan
- Ratchet and socket
- Transmission fluid
- Place the Hummer in a parking site with flat and level ground. Push the vehicle if needed.
- Chock the wheels to prevent the vehicle from rolling while you’re working on it.
- Turn on the Hummer’s engine and allow it to idle for a few minutes.
- Open the hood when it’s warm and not scalding.
- Place a drain pan underneath the transmission fluid container.
- Remove the drain plug from the transmission fluid container, which should release the fluid almost immediately.
- Return the drain plug after the container empties.
- Search for the transmission fluid container cap in the vehicle’s engine block.
- Remove the cap and place a funnel into the opening.
- Refill the container with the recommended amount of transmission fluid.
- Return the transmission fluid container’s cap.
- Turn on the Hummer’s engine and allow it to idle.
- Attempt to change the Hummer’s gear by shifting the shifter lever to check if the problem persists.
Check out this product on Amazon.
Note: Avoid refilling the Hummer’s transmission fluid when its engine is cold. Otherwise, you may need to go through additional steps to ensure the refilling process gives you the appropriate results.
Watch the video below for additional insights into this procedure:
Active Neutral Safety Switch
A neutral safety switch is responsible for preventing a vehicle from starting in any other gear setting except neutral or park. But this switch may also prevent you from shifting gears for your Hummer when needed.
How To Fix
Search for your Hummer’s neutral safety switch and disengage it. Consult your vehicle’s owner’s manual to find the switch’s location. Take note that you may need to go underneath the vehicle or take the shifter cable assembly apart to expose the switch. You might also need to replace the switch if it’s faulty.
Watch the short clip below for a quick guide on how to replace a Hummer’s neutral safety switch:
Check out this replacement Hummer neutral safety switch on Amazon.
Do Hummers Have Transmission Problems?
Hummer owners may encounter some relatively common problems with their vehicles. Some known transmission issues for Hummers, particularly the H3 model, are:
- Difficulty in shifting to the 2nd gear
- Gear change recognition is slow
- The vehicle doesn’t register the change to the 3rd or 4th gear
Failure to repair transmission issues or replace the faulty system may result in a complete vehicle stall. If the issue appears while you’re driving, your Hummer may also become a health hazard to you (as the driver), other passengers, and nearby individuals.
How Much Is It To Replace A Transmission In A Hummer?
If the methods mentioned in this post didn’t work, you may need to have your Hummer towed and its transmission system replaced. Prepare to spend about $2,000 to $3,500 for the replacement job. Take note that this price range generally covers the parts and professional labor needed for the task.
Is It Worth Fixing A Transmission?
It can be worth fixing your vehicle’s transmission, especially if you’re a proud owner of a Hummer. But bear in mind that repairing or replacing the transmission system of your vehicle may require fees that are approximately 40% to 60% of its value.
So if the overall cost to fix your Hummer's transmission system is almost or exceeds the vehicle's original value, it might be better to purchase a new vehicle than attempt repairs.
Check your Hummer's transmission fluid levels, the gear shifter assembly, and the vehicle's computer to find the reason why it doesn't change gears. You can then use one of the solutions mentioned in this post to help solve the source of the problem. Otherwise, you may request help from seasoned automotive repair technicians, particularly if you think the repair job is too much for you to handle.
If you’re looking for answers to other Hummer concerns, check out these other great posts: