Few things are more annoying to drivers than getting into the vehicle and turning the key, only to hear nothing in response. Fortunately, while starting problems can come from many sources, a failed starter solenoid is relatively common—and one that a lot of drivers may not be aware of.
Learning the warning signs of a bad starter solenoid will help you diagnose the issue quickly in order to avoid being stuck with a dead battery on the side of the road and save you hundreds of dollars at the mechanic’s shop.
Let’s look at the basics of this important component of the starting system and how you can tell if yours is starting to fail.
Starter Solenoid vs Starter Relay
There is, however, some confusion that exists over the difference between a vehicle’s starter solenoid and starter relay. This confusion stems from the fact that the two components differ from one another in more than one way.
While the starting solenoid controls the starting of the engine with the starter’s Bendix and completes the circuit way to the starter windings themselves, the battery starter relay, when closed, increases the current available from the battery to the starter and, thus, prevents the withdrawal from the battery of excessive current during the starting period.
A vehicle’s starting solenoid is usually mounted on the outside of the starter itself, forming part of the entire starter assembly.
On the other hand, a vehicle’s starter relay is usually enclosed in the under-hood fuse box and is much smaller than a vehicle’s starting solenoid. It plugs into the specified terminals in the above fuse block.
Bad Starter Solenoid Symptoms
In almost every case, a faulty or failing starter solenoid is accompanied by one or more of the symptoms that will prevent a vehicle’s engine from starting. Recognizing them is the first step to achieving a timely diagnosis.
#1. Silent when starting.
One of the most common of starter solenoid symptoms is that the starting system does not respond as it should when the vehicle start button is pushed, or the key turned to the “run” position.
In most cases, no actuation of the starter motor will be heard, nor clicking from the starter solenoid itself. In other instances, there will only be a single click.
#2. Intermittent “no-crank” events.
Another indicator of pending starter solenoid failure is intermittent “no-crank” events. If the engine in your vehicle sometimes fails to crank, only to start properly a few moments later, there is a high probability that the starter solenoid is at fault.
Such “episodes” can, unfortunately, escalate with time until complete failure occurs.
#3. Grinding of the starter when cranking.
It is also possible for a grinding noise to be heard if a starter solenoid is beginning to fail. Such is the case where the starter solenoid also controls starter-to-ring gear engagement and, should failure prevent full engagement, cross-alignment between the two surfaces can result.
Beware of False Online Information
Beware of ‘online’ misinformation when it comes to the diagnosis and repair of automotive problems. This is especially true of pages attempting to help troubleshoot starting problems.
Avoid any pages that confuse, or interchange, starter relay and starter solenoid. The two are not one in the same, and should not be used as if they are.
Avoid pages that tell you to replace a certain component because you “hear this” or “don’t hear that.” There is a diagnosis process to properly troubleshoot starting problems.
Attempting to replace parts in like fashion, without a solid diagnosis to rely on, is just throwing money at parts that you are replacing, but did not need to replace.
Replacement Cost
The cost for replacing starter solenoids will vary from one make and model of vehicle to the next. There is also some variation in cost associated with how, exactly, repair is dealt with.
While it is possible to only replace the starter solenoid, it is also common for the starter and starter solenoid to be replaced as a unitized assembly.
Assuming that you want to replace your starter assembly, as is usually the case, you can expect to pay somewhere in the neighborhood of $400-$750 to fix your starter solenoid problems.
However, significant money can be saved by doing the work yourself, as more than half of the above price is accounted for by labor alone. For the handy mechanic, even more money can be saved by replacing only his or her starter assembly solenoid (though this often proved a bit more difficult).
What Causes a Starter Solenoid to Fail?
A starter solenoid can fail for many reasons, but perhaps the most common has to do with typical wear and tear. Over time, the internal electrical contacts of the starter solenoid can wear, becoming less conductive.
Also, given the location of the starter/starter solenoid on most vehicles, water contamination and corrosion are a primary concern and a possible cause of failure.
It’s also important to note that all electrical leads and wiring to a vehicle’s starter solenoid should be inspected periodically. It’s not uncommon for voltage drop caused by poor electrical connections to cause starter solenoid-related issues.
Over time, this extra resistance in the starting circuit can take its toll on a vehicle’s starting solenoid, due to the additional heat generated.
Diagnosing a Bad Starter Solenoid
The following steps may help in pinpointing starter solenoid-related problems. Prior to commencing, it is advised to obtain a factory-specific service manual for your particular vehicle make, model, and year.
Step #1. Battery Voltage.
With your quality multimeter, check your vehicle’s battery voltage. The meter should be set to its DC voltage scale, and both leads touched to the battery’s corresponding posts as to polarity.
A battery should, ideally, read statically 12.6V.
Step #2. Voltage Drop.
With your meter and leads positioned as above, have an assistant attempt to crank your vehicle. Keep a careful eye on the reading on the meter. It should not dip below 9.6V. A drop greater than this would necessitate a new battery.
Step #3. Starter Solenoid Connections/Leads.
Carefully inspect all electrical leads at your starter/starter solenoid for loose connections or corrosion. Any underlying conditions of this nature should be repaired prior to continuing.
Step #4. Ignition Feed at “S” Terminal.
At this time, we will need to verify all inputs at the starter solenoid. We will first see that there is a 12V+ battery feed at the inlet to the solenoid. Presuming that this is the case, we will then see that there is 12V+ distributed to the “S” terminal on the solenoid, while an assistant attempts to crank the vehicle.
If a positive voltage is not noted at this terminal, suspect ignition switch or wiring problems. If this feed is noted, but the battery voltage is not at the outlet of the assembly, then suspect a fault within the starter solenoid. Confirm with continuity tests as in OE service literature.