2005 acura mdx slow crank

Maintenance/Repairs
1

so my 2005 acura mdx cranks slow and most of the time starts but there’s been times where it didn’t. The battery tests come back good. 12.6 car off, 10.5 while cranking, and 14.2 when running so alternator should be fine to. I also had autozone test it with a machine and everything including the starter came back fine. I’m thinking its the starter but what is the most efficient way to test the cables, grounds etc?

if my starter is cranking and starting engine but cranks slow, could it be any type of electrical issue or is it the starter itself?

2

You inspect the connections between the battery and the starter and the battery to ground.

Tester

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3

What did it do? just click?

Was it slow cranking while being checked also and still tested good?

4

no when it didnt it would just very slowly crank and not start. and yes the slow crank is very consistant it was slow cranking when i tested it (10.5 while cranking) and when the autozone machine tested it

5

There is a ground the connects to the frame near the front I think and one that connects to the engine block. I will check those and clean them and also check the positive connection to the starter making sure its tight before I go ahead and replace starter. thanks

6

Also check the connection at the starter.

Tester

7

Did anyone measure the amperage draw? I don’t think Autozone does that.

10.5 volts while cranking was normal 50 years ago, starter motors today draw less than half the current, the battery voltage should be 11.5 or higher while cranking. When the battery voltage drops to around 10 volts, the PCM won’t allow the engine to start even though the engine is cranking.

The starter motor has an internal short or the battery has insufficient cold cranking amps.

8

the engine starts basically every time just cranks slow

9

the battery is 12.6 with engine off every time i check it. if there was an amperage draw wouldn’t the battery be dead or lower than 12.6 every time I check it?

10

Measure the amperage draw of the starter motor while cranking the engine, should be about 100 amps.

11

Your shop could measure the voltage right at the starter motor terminals. Ask them to measure both the thick and thin wires, when the key is in start. Probe directly between the terminal and the starter motor case. What voltages do they measure?

12

At any rate, I’d feel better if a dealer checked it out, but I wouldn’t buy a starter at Autozone if I were determined just to replace it.

13

Are you suggesting that a driveway weekend diy’er should attempt that measurement?

14

They make starter current draw testers for the DIY’er.

Just lay it over the positive cable to the starter, and have someone crank the engine over to measure the current draw.

Tester

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15

Do it yourself or have it repaired, these are the choices.
Inductive amp probes/meters are available at many different price levels.

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16

Replaced the starter and it fixed the problem. If anyone is having a very consistent slow crank but engine is starting, replacing the starter fixed it for me.

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17

That suggests the problem was the starter’s solenoid contacts. The starter motor has heavy duty electric-current switch inside, and the contacts pit and otherwise degrade with use. The contacts are somewhat similar to a spot welder. It is also possible one of the windings was faulty . In any event you were wise to replace the starter, b/c pretty soon it probably wouldn’t crank the engine at all. Good for you for getting it resolved!

18

Or the brushes in the starter were worn.

Tester

19

Here is a pretty good video of how a modern day starter works…