Can you diagnose this car problem?

Factual Questions
1

Because the mechanics can’t after 3 tries. 2006 Jeep Commander

Intermittant but getting progressively worse. Turn the key. Click. Nothing.
They’ve tried battery, spark plugs, claim to have tested the alternator, starter I think. Everytime it comes back fixed but within a few weeks the problems start again.

New symptom.: yesterday the click click with a few tries then the next two times it was cranking but getting no gas, even with pressing the pedal down. That happened twice then it started on the next try.

2

Intermitants are the toughest things to find. I once traced problems in my truck’s fuse box by letting the truck set and idle until it died. You must test when the problem exists.

Do you have a helper? Checking for power at the start terminal of the solenoid when it fails to start will tell whether the problem is before or after it. If the cluster lights fail to come on when you turn the key on, check back to the fuse.

3

Failing to crank and cranking without starting are two different things, and you’ve got both (though not apparently at the same time?) so you may have more than one problem.

When the starter goes click click click click that means the solenoid isn’t engaging. The clicking noise is the solenoid. There are a lot of reasons it might not be fully engaging and starting to crank. You could have a weak battery (which could be caused by many things). You could also have a bad connection somewhere between the battery and the starter, or within the starter itself. Take a look at all of the cables involved and look for a loose connection or a corroded wire. ETA: Could be that the starter itself is going bad, too.

Cranking but not starting is a different problem. The old saying is that a car needs two things to start, fuel and fire (electricity). There are a lot of possibilities here as well, like a bad ignition module or a bad or weak fuel pump or some sort of wiring problem between the battery and the fuel pump.

The only way I can see them being related is if you have a weak battery, and when it manages to get the engine to crank it has somehow not provided enough power to the fuel pump. Corroded connections in your electrical system could cause this as well.

What’s the voltage on your battery and without starting the engine, what’s the voltage on the battery when you turn the lights on?

A weak battery could be caused by the alternator not charging it properly, which could be a bad alternator, regulator (probably built into your alternator) or a bad electrical connection somewhere. A weak battery can also be caused by something not shutting off when you switch off the engine, and the battery gets drained while it is sitting overnight.

Is the problem worse in humid weather or when it is raining? Is it worse on Monday if you haven’t driven over the weekend?

4

I’d bet it’s electrical. Between the ignition switch (is it one of those new transponder types?) and the starter solenoid. Is the battery fully charged and does it hold a charge?

5

has anyone checked the battery cables? specifically looking at the ground straps where they attach to the engine?

6

I had a completely different make/model/manufacturer car with a similar problem and it was the ignition relay. (Easy, cheap fix)

So I just searched “2006 Jeep Commander relay” in Google, and some of the relevant results were:

Hope this helps.

7

I’m onboard with your diagnosis here. If the battery voltage drops under about 9.5 VDC while cranking, the electrical system will not produce a spark. The fuel pump will probably run because it is not as voltage dependent as the ECM. The battery could be weak or the starter may have a heavy draw. I vote for the battery. Could it even be original as a 2006. If so, replace it without checking anything further and go from their. You cannot trust a five year old battery, period.

8

Replaced the spark plugs for a no-crank problem? No wonder they can’t fix it. That’s ridiculously ignorant. In all seriousness, if they actually put new plugs in with even the slightest hope it would help with the symptom described, don’t go back there. They’re too stupid to count to two.

If there’s a single click when the key is turned to the start position, that indicates that the ignition switch is energizing the starter circuit. Given that click and an intermittent no crank, the starter is the prime suspect. It can be accurately tested when the symptom is present. Testing is useless when the symptom is not present. If it can be caught in the act, a competent mechanic can determine the cause of the problem.

If this has only happened once so far, it may have just been a fluke. Pressing the accelerator pedal generally does not help in starting on modern fuel injected vehicles. On most systems, pressing the pedal to the floor actually disables the injectors (it’s a “clear flood” mode).

9

Gary T while I agree on the crappy diagnosis, isn’t changing spark plugs something a mechanic does every time he opens the hood? (easy, fast, cheap, can’t hurt)

10

no. where did you get that idea?

11

x2 on checking your battery cables, easy way to check, when it will not start, either cranking or not, find out what happens when you hook up jumper cables, if it starts I would check the connections at the battery, if problem persists check the other ends at the starter and ground.

12

These cars are known to have issues with both the ignition switch and the WIN module.

I had a customer with a 2007 Commander where the WIN module failed just after I installed a remote starter…it was a challenge to help the Jeep dealer perform a proper diagnosis and cover it under warranty.

If you go to google and just start to type in “jeep commander ig…” you should see what the autocomplete is.

Anyway, no parts should be replaced without a proper diagnosis. I agree with GaryT that whoever you took the car to has no clue.

You did say that you have “nothing” when turning the key, but whether we do this over the Internet or you visit a mechanic in person, more questioning and diagnosis is required.

I’m still finishing my morning coffee and I apologize for my long-winded, rambling nature, but hopefully the following should point you in the right direction.

Since the mechanic has obviously failed to perform neither a question-and-answer session with you, nor a proper diagnosis, you’re going to have to do a little of it yourself…nothing scary and no tools necessary.

First, when the car is operating correctly, you should familiarize yourself with its normal operation. Perhaps you already know this, but let’s go through all the normal functions:

  1. Open door, insert key in ignition but don’t turn. You should hear the warning chime that you “forgot” the key in the ignition with the door open.

  2. Turn the key one click forward. The chime should keep going, and you should be able to play the radio.

  3. Turn the key forward one more click. You should hear the 5-second seat belt chime, then the noises should stop. The instrument cluster should have all/most of the warning lights lit up like a Christmas tree.

You should be able to operate accessories like the heater, power windows, and so forth.

  1. Turn and hold the key forward all the way. The radio and heater should turn off, and the engine should crank and start. Release the key and the radio and heater should come back.

(NOTE: You could also, if you’re curious, sit in any friend’s car and do the above. Most cars work the same in this regard.)

Anyway, so know you know how it’s supposed to work…

Next time the car fails to start, check and observe the following:

  1. Does the keychime work?

  2. Can you operate the radio with the key in the Accessory position?

  3. With the key in the Run position, does the dash light up and can you use the heater and windows? (Obviously with a cold engine, the heater will only blow cold air; the test is just to see if the fan operates.)

  4. When turning the key to Start, the accessories should all turn off. Do you hear any clicking sounds under the hood?

  5. As a very crude test to see if you have a dead battery or not, do the domelight and/or headlights shine brightly? Do they become very dim when you try to start the engine, or do they still stay almost as bright as before?

Summarizing…

Based on your first post, you may have a car that turns on its ignition just fine but doesn’t crank the starter, or a car that doesn’t turn its ignition on at all. It’s impossible to know where to start looking until you know which is wrong, but in general:

No ignition: ignition switch, connectors at ignition switch, fused power going to ignition switch, et cetera.

Ignition comes on but no crank: starter motor, cabling going to starter motor, ignition switch.

Anecdotes…

As I said above, proper diagnosis is the key, not firing parts randomly at the car until the problem goes away.

However, these cars do have some known problems:

A. Google “jeep commander starter” and look at the autocompletes. These cars do have some starter issues.

B. I seem to remember some customer’s car where the cable at the starter had come loose, but I don’t know if it was even a Commander or not.

C. These cars do have issues with the WIN module. However, a defective WIN would cause your keyless entry not to work, and also the car would start and die…not fail to crank at all.

The WIN is just behind the ignition switch, and includes an antenna “ring” around the ignition keyhole behind the plastic trim.

The WIN serves both as the keyless entry receiver, as well as part of the Sentry Key system to make the car harder to steal.

Again, a faulty WIN would leave you with no keyless entry, and also the car would start, run for about two seconds and then stall…with a small red light flashing in the instrument cluster.

If you suspect the WIN at all, next time the car fails to start AND you’ve determined the car’s battery is not dead, try the keyless and see if it’s still working.

13

No. Service intervals for spark plugs range from 30K miles to over 100K. And on some designs, it ain’t cheap.

14

Chrysler minivans with V6s. gotta love changing the rear bank of plugs; always easiest going from under the van while hugging the exhaust system.

15

The said the throttle body was dirty and they cleaned it. :confused:

16

I’m confused too. It might well have needed a throttle body cleaning, but there’s no way that had anything to do with the failure to crank, and it’s quite questionable it had anything to do with the failure to start when cranking.