Transmission Shift Solenoid Test – Diagnosing and Repairing

If you’re an enthusiast, then it’s your duty to be comfortable with getting your hands dirty. Not only does that inculcate discipline and respect for that machine in front of you, but it also lets you get the job done without consulting a professional.

With that note in mind, the purpose of this segment is to go over how you can undertake a complete transmission shift solenoid test.

However, before we begin, let’s go over the basics once.

What is a transmission shift solenoid?

What is a transmission shift solenoid
Introduce transmission shift solenoid

A transmission shift solenoid, just as the name implies, is responsible for shifting gears in your vehicle. Thanks to recent breakthroughs in the industry, automatic vehicles have been the new storm.

With their main feature being self-adjusting gears, the driver doesn’t need to worry about a thing. Transmission shift solenoids make that happen (However, this is also applicable to manual vehicles)

This apparatus constantly takes in feed, such as the vehicle’s speed, information from the engine, and other parameters that allow it to carefully deduce when to step up or step down a gear.

When it comes to making the shit, the control unit sends out an electrical impulse, or a signal, that shifts the required solenoid and opens it. This allows for the influx of the transmission oil, and voila, the job is done.

Diagnosing your transmission shift solenoid

Diagnosing your transmission shift solenoid
Transmission shift solenoid Diagnosing

This is the easy part. To discern if there’s an issue or not with the transmission shift solenoid, you’ll notice symptoms long before things escalate.

Here are the main things you’ll need to watch out for!

  • Gear shifting is delayed
  • Transmission stuck at neutral
  • Rough and choppy gear shifting
  • Unable to downshift

These are the main things you’ll have to watch out. In all cases, we highly recommend that once you notice any of these things, it’s best to take matters into your own hand and get it sorted before something bad happens.

Testing the solenoid

Testing the solenoid
Solenoid testing

Now, let’s get to the heart of things. Note that in this segment, we’ll only be going over the basic tests you can use to find out if something is wrong or not.

If you suspect that somethings up and want to make sure, this is how you’ll go about it. However, fixing the thing is an entirely different thing.

Here’s how you go about testing the transmission shift solenoid!

1. Safety first

Safety first

The first step that you should undertake, which should be ingrained into your memory, is taking the right safety precautions before beginning.

The ignition, in all cases, should be off. If not, you seriously run the risk of damaging something or, worse, hurting yourself.

Since you’ll be under the car, it’s a good idea to wear something comfortable that you can freely move around in. Goggles are entirely optional when testing the transmission shift solenoid. However, if you want to go the extra mile, it’s a good idea to keep them at hand.

2. Equip yourself

Equip yourself
Get equipped to car repair

The next step is to have the appropriate tools with yourself that you’ll be using.

The two main things that you’ll require are the ratchet set and the voltmeter.

The ratchet, of course, will be used to pull apart the delicate machinery so that you can get to business. We don’t suggest that you keep the whole set with you the whole time, just get the main parts ready, and you’ll be good to go.

The voltmeter is super important in this task as well. You’ll be using this to test the resistance, something that we’ll elaborate on shortly.

You can either choose to calibrate the voltage to the desired output before or once you’re under the vehicle, that’s entirely up to you.

3. Read the manual

This step is rather elementary, but we want to highlight it for one main reason.

Generally speaking, the manual will give you a rough chart or a map that can help you easily locate the transmission solenoid on the particular vehicle you’re working on.

4. Raise the vehicle

Now, let’s get to the real part.

Using a jack, raise the vehicle up to a comfortable level and then support it on all fours.

Once done, slide underneath your car, and remove the bolts that secure the transmission oil pan. The instruction manual will help you locate that since the position of this pan isn’t standardized.

Slide-out the pan and place it securely if it comes off. This will reveal to you the solenoid that is attached to the transmission body.

5. Locate the plugs

Locate the plugs
Plug location

Locating the plugs won’t be that hard. They are located just above the shift solenoid. Grab ahold of them, and they unplug one.

One common mistake that people often make is that they unplug both the plugs, which just makes the whole situation a little tough to deal with.

For a smooth and flawless operation, we suggest that you proceed with one first.

6. Activate the voltmeter

Next up, set the voltmeter to measuring resistance and then turn the knob to 200.

You can either choose to do this beforehand or do it on the spot – that’s entirely up to you.

If there are any discrepancies in its measurement, there’s a risk you could be on the path to misdiagnosing the solenoid completely.

7. Grab the black wire

Grab the black wire
Grab the black wire

Once you’re confident with the voltmeter, grab the black wire from it and touch the negative battery terminal.

After that, attach the positive end of that wire to the tab inside the plug that you just located and then proceeded to unplug.

Once done, get the reading off of the voltmeter.

If the reading is between 12 or 25, that means there is nothing wrong with the machinery, and the culprit might actually be something else. However, if the reading is below it or over it, that means the shift solenoid is bad.

However, this isn’t all of it.

You still need to check the other plug to see if the readings are consistent or not. If the two plugs show different readings but still are under normal, then you’ve got nothing to worry about on this end.

8. Check the other plug.

Check the other plug
Other plugs

Checking the other plug shouldn’t be that hard, and you’ll have to follow the exact same steps as above.

As mentioned above, if the readings are different but in the normal range, then you’ve got nothing to worry about, and everything is working just as it should.

However, if the readings are off, and one plug gives a different value above or below the optimal range, then you’ve got a problem.

In this scenario, it’s a good idea to get the whole unit replaced and start fresh.

9. Reseal

Once you’re done with the inspection, whatever the result is, you’ll have to reseal it.

Repairing the transmission shift solenoid

Repairing the transmission shift solenoid
Repairing the transmission shift solenoid

The good thing is that we now know how to test the transmission shift solenoid, so we know something’s wrong for sure.

When it comes to repairing the transmission shift solenoid, there are several things that can be done. Since the machinery is a little intricate, more than one thing can go wrong.

Hence, if you’re planning to repay the transmission shift solenoid yourself, you first need to assess what’s wrong.

Now, we’ll list down the major culprits and briefly go over how you can go about fixing the issue.

Shifting delays

The major reason why you might experience shifting delays is due to a faulty shift solenoid. This is it; there’s literally nothing else.

And hence, the only solution for this ailment is that you’ll need to get the whole unit replaced.

Make sure that you get the exact same size and unit so that installation isn’t an issue. One good thing about this is that the new unit will come with a manual, so you won’t have to worry much about getting the details right.

Stuck in gear

Stuck in gear
Stuck in gear

While driving, if you feel that your vehicle has stuck in gear, the main problem could be related to the wiring.

In other words, the electrical transmission might be a little faulty, which would make it impossible for the unit to perform at full capacity.

Luckily enough, this has a simple fix. Just clean the connection out from below, and you’ll be fine!

Engine light/limp mode

When it comes to this, you’ll need to replace the Transmission Control Unit, also known as the TCU.

There’s no other way to work around it, unfortunately. You can choose to install the new unit yourself, in which case always check for an instruction manual, or have the job done professionally.

Downshift/Upshift problem

Downshift/Upshift problem

Downshift and upshift gear-related problems are mostly caused due to faulty wiring to the shift solenoid.

Since the electrical relays aren’t consistent or are sporadic at best, you’ll notice this problem right from the start. It can also make driving pretty dangerous, so if you feel this is an issue, address it ASAP.

The best course of action for this is to check, test, and repair the wiring between the shift solenoid and TCM.

Skip/Jump over gears

Skipping and jumping over gears is a clear indicator of low transmission fluid.

There’s nothing much that needs to be done when it comes to this. Just check the transmission fluid level, refill, and you’ll notice a change immediately!

Optional cleaning

Optional cleaning
Optional cleaning

If you’re already underneath and want to take things a step further, you can also clean out the whole system underneath.

Due to dirt and dust creeping into the transmission system, performance can often be affected. If you’re looking for a quick fix, this might actually do the job for a little while. Plus, this will also ensure that your transmission shift solenoid is kept in the long run!

Final Thoughts

We hope that the steps and processes mentioned above are more than enough to get you through. If you’ve tried our steps and have feedback, or would like to add any general comments or suggestions, do share them in the comment section below!

1 Comment
  1. hello . the issue i am having is that my vehicle only works in reverse , not forward. i have a 2017 chevrolet express 2500 4.8L.
    is it the shift solenoid?


Leave a reply

Automotive News, Guide & Advice | AutosGuide