Can A Bad Alternator Cause Transmission Problems?

If you have a bad alternator and the vehicle battery gets low on voltage then the computer may not shift the transmission gears correctly and cause other drive symptoms like stalling or surges and rough shifts. Engine and transmission may even go into failure mode and cause various drive symptoms. Don’t worry the article discusses can a bad alternator cause transmission problems? Learn how to fix this problem?

Can A Bad Alternator Cause Transmission Problems?

Your car’s alternator is a small generator that helps pump electricity back into the battery as you drive. If the alternator fails, the battery isn’t getting recharged quickly enough (or, in some cases, at all).
Your car’s automatic transmission uses a computer to help the transmission shift between gears. The car’s battery getting too low has the same effect on the car’s computer as your brain not getting enough oxygen—some miscalculations are going to happen.

The result here will be rough shifting, the engine stalling out, or the engine downshifting early and rocketing the car forward faster than you expect. The car might just feel jerky when it shifts, too.
If you’ve taken your car to a professional, certified mechanic and they’ve identified the alternator as the culprit for your transmission woes, we’re prone to trust their expert assessment. They should have diagnosed the issue carefully and cleared the usual suspects from the list before concluding it was the alternator, and then tested the alternator to verify the problem.

What Symptoms Does A Bad Alternator Cause?

  • Dim or Overly Bright Lights
  • Dead Battery
  • Slow or Malfunctioning Accessories
  • Trouble Starting or Frequent Stalling
  • Growling or Whining Noises
  • The smell of Burning Rubber or Wires
  • Battery Warning Light on Dash

Can A Bad Alternator Cause Acceleration Problems?

The falls in the electrical power of a broken alternator can cause a malfunction of these systems, leading to a malfunction of the engine. Symptoms will be the slowing down, the failure, the poor acceleration, the hesitation and the stalling.

Will Your Car Start If Alternator Is Bad?

Cranking Troubles And Frequent Engine Stalls A failing alternator will have trouble charging the battery. In turn, the car battery won’t have enough power to start the vehicle. If the engine stalls almost immediately after a jump-start, then your car’s alternator is the likely root cause.

What Is The Average Life Of An Alternator?

“Its primary job is to keep the electrical system up and running in place of the battery. The battery’s job is to start the car, and the alternator keeps it running.” Gunning says an alternator typically lasts about seven years — or about 100,000 to 150,000 miles, says Waits.

Do Alternators Fail Suddenly?

The alternator is a key component in running the electrical systems in your car. When your alternator begins to fail it can cause a variety of different electrical problems in your car, and eventually cause a breakdown. Alternators can go bad suddenly, or slowly over time.

How To Fix A Bad Alternator?

Before You Start, Purchase The Right Kit For Your Alternator

The assumption is that you have already purchased a brush and regulator replacement kit for the model of alternator you have before starting this instructable.

Safety First, Disconnect The Car Battery

Disconnect the +ve from the battery for safety, I did not do this and bumped a +ve wire connected on the Alternator which created some brief fireworks, so my advice is to disconnect the +ve on the car battery first.

Remove The Alternator

Take some photos of the alternator in position and the orientation of the wire harness, ie the wiring socket at the rear of the alternator. Before unbolting the alternator ensure you unclip the wire harness on the rear of the alternator.

You may have to google for details depending on the make and model of your car. But typically two bolts hold the alternator in place, one long pin bolt on the underside of the alternator and a short bolt through a slotted bracket on the top of the alternator. Unbolt both, the long pin bolt might take a little effort to remove, but with patience and persistence, you’ll get there.

Remove The Rear Cover On The Alternator

Now you have removed the alternator, remove the plastic cover on the rear of the alternator, typically there are two bolts to be removed to remove the cover.

Remove Old Regulator And Brushes, Fit New Kit

With the rear cover on the alternator removed, take some photos of the regulator, and wiring to and from the regulator and the brushes. These may be handy should you have issues refitting the wiring.

Now remove the old brushes and the old regular ones. When removing the brushes check the length of the old against the new to see how much the old have worn.

Install the new regulator, and note wiring instructions from the supplier with the upgrade/repair kit. Install new brushes, reconnect wiring and refit bolts, and tighten (be mindful not to over tighten as the bolts are probably screwing into brittle plastic). Double-check wiring against your previous photos and the instructions that came with the kit.

Refit Black Plastic Cover

Refit the Black plastic cover to the rear of the alternator.

Refit The Alternator

Refit the alternator back into your vehicle and make sure the fan belt is tight.

Now Run Some Tests To See If You Have Fixed It

Attach your multi-meter +ve to car battery +ve and multi-meter –ve to car battery –ve, and set the multi-meter voltage range to 20VDC or the next above whichever is available on your multi-meter.


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