Troubleshooting Allison Transmission Shift Selector Problems

It may not always be a simple problem. Usually, you start with all the simple possibilities to fix a problem. This spares you the embarrassment of paying a technician for something you could have fixed in two minutes. However, sometimes the source of your problem is complicated and needs a technician’s touch.

You can look at corroded connectors, blown fuses, or a bad wire to see if these are the source of your shift selector problem. However, sometimes it turns out to be the actual display that is faulty and will need replacing by a skilled technician.

To learn more about this situation, just continue to read our article. It provides the information you want to know about so you can get to the heart of the matter quickly. Once you find the source, you can assess if you are able to fix it or if you need to call in a professional.

Common Allison Transmission Shift Selector Problems


Here are 6 shift selector problems most Allison transmissions come with:

1. Delayed shifting- the source for this issue is twofold. One, there is a problem with the air intake. Two, there is a problem with the transmission fluid. Check for leaks and keep the fluid topped up for better shift results.

2. Shift jerk- this problem comes from when the transmission fluid has gunk in it. The solution is to drain the transmission fluid, flush the part with a cleaner and then replace the old fluid with new.

3. Misalignment between gears and shifter- these problems usually show up when some repair work has already been done. The shifter cable is either too long or too short. You have to adjust the cable or get a new one.

4. Weird noises- if you hear a whiz, hum, buzz, or a clunking noise then go to a mechanic. There may be a leak somewhere and it needs to be patched as quickly as possible.

5. Stuck gear- usually this is when you are low on transmission fluid or you have added a thicker fluid than is necessary.

6. Slipping gears- the transmission gears are just wearing out. The cause of this problem is overheating the transmission or not keeping the transmission filled with fluid.

What Would Cause an Allison Transmission To Not Shift in Gear?

There are 4 good reasons for this problem to occur:

1. The transmission fluid- the level of the fluid is going to be the biggest concern here. If it is too low then it can’t lubricate the gears well enough and that can stop the transmission from shifting.

Overfilling the transmission will cause you a lot of problems as well. Then if the fluid needs changing because it is full of gunk, that will stop the gears from shifting.

2. The wrong fluid- there is a reason why transmission makers recommend certain fluids for your transmission. Anything other than what they recommend is the wrong fluid to use.

When you do that your gears and transmission won’t work right. Make sure to always use the right fluid and only fill it to the full line.

3. Low temperatures- cold regions of the country will affect your transmission fluid. The colder it gets the more likely the transmission fluid will thicken and not flow correctly.

To fix this, you just have to warm up the engine and transmission before you start driving. There is nothing else you can do about this situation.

4. The transmission is damaged- if you are not an expert on this vital and expensive part, then take your car or truck to the experts and let them diagnose and fix the problem.

Allison Transmission Shift Selector Has no Power

When there is no power, it usually means that there is an electrical problem. The first place to check would be the fuse. If it has blown then all you need to do is replace it. If the new one and subsequent ones continue to blow then you have a bigger problem on your hands.

The fuse for the shift selector can be in the front electrical bay. This bay is located on the outside under the driver. Or it could be in the inside compartment to the driver’s left. Next to the shifter panel.

Another possible problem can be that the wires are corroded, loose, or broken. They can also be bad. If the fuse is intact then check the wires for any problems. Clean or replace any bad wires or corroded connections and so on.

If there is still no solution you may have to call in a technician to look for more complicated to fix issues.

Allison Transmission Shift Selector Flashing


Not all flashing lights indicate that something major is wrong. Sometimes, like in this instance, they are just letting you know that the transmission fluid is too low. All you have to do is fill the fluid tank to full and you can be on your way.

However, those flashing lights may indicate a major problem as some owners have found out. One had a bad pump that had to be rebuilt when his D started to flash.

Another owner found out that he had a transmission module problem and needed a new one. The bad news for him was he was dealing with a fairly incompetent dealer. He went through a hassle to get the right fix.

This is a problem you may have to deal with. Some dealers are not honest and will lie to you. This particular one said there were no error codes so they could not fix the problem. Turns out they had 2 error codes and then fixed the truck right away.

Try to be careful where you take your truck when you see the flashing D or R on your selector.

Allison Transmission Shift Selector Not Lighting Up

Again, this is usually an electrical problem and you will need to start looking at the usual suspects. Those usual suspects include wires, fuses, connections, and so on. It is going to take time in some cases to track down the problem.

Or the problem is specifically in the pair of wires coming directly from the engine to the VIM. There can be an open short at this spot which is cutting off your power.

Another possibility for this problem would be an issue with the harness between the ECU and the shift pad. But these are just 3 issues and you should look for an inline fuse in the system to make sure that is not causing the problem.

One more possibility would be the solenoid. If it goes bad, then you would not have any power to the pad or to the engine. You should not be able to start your truck or RV when it goes out.

If the solenoid is good, then test the relays and see if they failed. Once you find the broken part, just replace it so you can get back on the road again.

What Would Cause an Allison Transmission Limp Mode?

This is the problem with having your engine and transmission controlling everything. Once those devices detect a small or minor problem they put the vehicle into limp mode.

Limp mode is simply a safety feature to protect your engine or transmission. Some causes for this situation would be your engine severely overheated or you are towing a very heavy load. Other causes are in the following list:

- Transmission errors (for example, being unable to change gears properly).

- Boost control issues.

- Brake malfunctions (for example, the hydraulic leak in the brake system).

- Engine issues (for example- turbo problems or engine misfiring).

- Sensor malfunction

- Oil levels or coolant levels are deficient

- Wiring issues (source)

The signs you are in limp mode include:

- Related functions like air conditioning and heating may stop operating.

- Check engine warning light illuminates.

- The maximum RPM will be limited (approximately 2,000 to 3,000 RPM).

- Allison locked into a low gear, usually the 3rd gear, but it depended on the model.

- Reduced performance

- The vehicle’s speed will be limited to 35-55 mph (same source)

When you are in limp mode do what everyone else does and take your vehicle to a qualified and approved mechanic to fix the problem.

Transmission Shift Selector Codes


The good news is that the manual for this transmission shift selector has all the codes you need to know about when something flashes on the display screen.

The bad news is that the number of codes goes from page 17 to page 21 in the hard copy version. If you click on this link, you will get to the manual at our go-to manual website and the codes will be found on pages 19 to 23 (not the manual but the website pages).

The link will take you to page 19 of that website manual. Then, this link will take you directly to the pages that hold the code and you can view them by scrolling and not waiting for a page to turn.

The drawback to this list of codes is that there seem to be several codes for the same issue. That is something you may have to figure out when the time comes.

How do I Reset My Allison Shifter?

The manual lists 2 prognostic reset instructions within its pages. They are found on pages 9 and 12. You may be able to use those instructions but if they do not work, it is possible that some of the codes will reset themselves.

Other codes may be reset just by pushing the mode button and holding it for 10 to 15 seconds. Then if the codes still remain, try doing an ignition cycle to clear the remaining codes.

If all else fails talk to your local mechanic who is familiar with this type of Allison transmission. There are some codes that have to be reset manually, according to the manual. One of those is the transmission health monitor.

In modern pieces of equipment like Allison transmissions resetting becomes an issue when the process you pick does not work. That is why it is always best to talk to a mechanic to get the right procedure to follow.

Allison Push Button Shifter Reset

These instructions are also for the bump lever shifter and the key instruction is once you start the process do not delay more than 3 seconds. If you do, you may have to start all over again.

The key should be in the ignition and turned on. But the engine has to be off. A very important piece of the process. While it is natural to want to turn the motor on, resist the desire and just leave the ignition in the on position.

Next, you push the buttons N-D-N-D-N-R-N. There are other sequences to go through for other parts.

Allison Transmission Shift Selector Not Working


Most likely this is an electrical problem and the transmission ECM fuse should be the first place to look. Even if it looks good, you should replace it as it may be corroded.

Then check any wires going to the ECM and look for corrosion or other problems with the wires. Finally, if everything electrical is okay, your shifter may need to be replaced.

It happens and you should be able to find a replacement at most auto parts or other parts stores.

Some Final Words

The technology that goes into the vital RV and truck parts can be daunting when they break down. Sometimes they are hard to fix and other times, you slap your forehead and say I should have known. Those fixes are very easy.

But when you are in doubt, make sure to find a reputable and honest dealer to work on your vehicle. That way you can avoid delays and have your vehicle back in a matter of hours and not weeks.

Then make sure to have a manual handy so you know what the codes are telling you.

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