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Discussion Starter #1
Hey group-

2003 MDX Premium - 217k miles. Been through lots with my girl, now she has me stumped...

Running fine, then last week went to start got a Rapid Click - immediately thought battery.
-Battery checks out fine
-Cleaned the terminals - same
-Removed and cleaned the chassis ground connections-same
-Replaced the starter - first attempt - same click. Second attempt it started. let it run for 10 minutes, went back to clicking.

4 days later- i have it in the driveway and have attempted about 20 starts, has started 18 of the 20 times.

There is a rapid click coming from driver side under dash when it doesn't engage.

Question - is there a starter relay that I should be chasing down?

Also- AC Compressor / fans not engaging now when AC turned on. I figure the fans should turn on even of the AC clutch is spent. Checked the AC fuse under the hood and it checked out.

Feel like i'm chasing electrical problems here. Any thoughts?

BTW-If anyone every gets sporadic rough ride throwing P300 codes- check the ignition coils. And DON'T buy aftermarket cheap ones. Better off buying used GENUINE Acura ones.
And yes- The transmission fluid connector to the radiator breaks off at around 165k miles - not a beast to replace, but takes some patience. While you're there do the front engine mount (again).

Thanks for any insight....
 

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Had the same first time ever about 2 weeks ago, what are the odds?! It was weird, as the car had power for lights, doors, radio , etc, all working fine. Turning the key, all I got was just the solenoid clicking without engaging the starter. I was able to jump start the car using my other car. Went to work, at the end of the day same clicking. Jump started it again in the parking lot and went straight to Costco and got a new battery. No problems since. Old battery had 11V and barely any Amps, 5 years old, Acura brand. So most likely what you need is a new battery :)
Anyway, how old is your battery? Did you check the Amps or just the voltage?
 

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For starter, there is an ignition coil relay under the dash. See the picture. You can google the image if you need better a quality one. Pic is for an 03. In case it helps, I have an 06 and the housing for the same is brown.

Assuming your Freon level is good, for the AC, it’s worth checking the AC clutch relay in the main fuse box in the engine bay. It’s usualy labeled, “mag clutch” or something like it. You can swap it with the same type relay that you know is working (horn, headlight, etc). There’s also a way to remove the relay and short the connection but I don’t recall the terminals. Google or search this forum if you want to try that way.

Thanks for the tips and good luck!
 

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I'd suggest that it would be worthwhile to get a voltmeter and a couple alligator clip leads to hook up to strategic places, to prevent the time-honored principle of throwing new parts at the problem. ;-)

I'd suggest doing the following tests with the voltmeter, with the only results you really care about being those when the car "just clicks" (which can be compared with the readings you get when it actually starts, as a bonus).
1) Across battery (probably not the issue, but I've seen batteries fail intermittently like this). If the voltage drops when the car won't start, get a new battery.
2) Battery negative terminal to starter main red lead. If the voltage drops dramatically when the car won't start, you have a bad cable / clamp / connection.

3) Battery negative terminal to starter "small red wire" (this is the "control wire" that tells the starter to engage). If the voltage drops when the car won't start, then you start tracing backward through the (numerous) connectors / cables / modules). Let us know and we can point you in the right direction.
4) Battery negative TERMINAL (not clamp) to engine block. You should read almost zero volts under all circumstances. If the voltage reading increases to more than a small fraction of a volt when you try to start the car unsuccessfully, you have a bad battery cable clamp / cable / dirty - corroded connection to the engine / body).
 

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Discussion Starter #5
Went as far as measuring voltage to the solenoid wire. It was going between 0-12v in sync with the clicks. That’s where I decided to look for relay. I did find a YouTube showing a solder joint gone bad, which gave me more conviction.

I’ll go back and do the full measurement string suggested and come back to the group.

Thanks for the direction comments all-!
 

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Discussion Starter #6
Oh - and battery checked out fine. Tried jumping on first instance of problem.

Had it checked at AutoZone- went to cleaning connections after that was confirmed.
 

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The starter relays seems to be #25 in the under-hood fusebox. It's a normally open "A type" relay, so there are plenty of others to swap out with it (the quickest way to troubleshoot).

If that doesn't work, the first thing I'd check is whether there the signal TO the relay matches the signal FROM the relay. The two contacts near and parallel to the edges of the relay (#3 and 4 in the diagram) are the input - try to measure the voltage across those terminals and see if you're getting solid or intermittent voltage. If solid - move forward, if intermittent (matching the clicks), you'll have to work back.

The first step in moving forward is to measure the voltage on the two other pins - one should be a voltage supply (12V DC I think) and the other is switched with the relay. Which is which should be obvious with a voltmeter (the source won't go anywhere - if it does, then you need to trace back from there). If you DO have solid input to the relay and intermittent / low output (low being less than the source on the other pin) then you know your relay is toast (but you already knew that if you swapped it with the horn relay, for example). ;-)

 

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Discussion Starter #8
Latest update

I spent the weekend trying to recreate the problem. Each time I would go to start it, it would start right up... until 10:00pm last night (was taking out the garbage). Went to start it-rapid click (including interior lights which has been consistent, I just didn’t mention it before). I went to get the voltmeter to take a few measurements, kept starting again.


Just tried again this morning and it started right up.

I’m struggling to find the ignition/starter relay. I didn’t see it in the engine compartment fuse box (mounted on the firewall, passenger side), and only see 2 relays mounted in the cabin above brake pedal. Any clarity would be appreciated.

Thanks
 

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Driver’s multiplex control. (You can also google for an image of it.)

For your ignition issue, looks like the ignition switch and ignition key light are one of the systems wired through it.
 

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Discussion Starter #12
Wanted to come back and close the loop on this for future users:

HabbyGuy had it right:
Battery negative TERMINAL (not clamp) to engine block. You should read almost zero volts under all circumstances. If the voltage reading increases to more than a small fraction of a volt when you try to start the car unsuccessfully, you have a bad battery cable clamp / cable / dirty - corroded connection to the engine / body).

My mistake is that I measured to the casing of the Starter and saw no drop. I also took a jumper cable to the Starter casing and got sporadic start/clicking. Took it down to my local garage, he heard the clicking. Without looking any further, he connected the Negative Battery Post to the AC Hose connector (metal piece) and it started right away - no issues - repeatedly.

Turns out the Engine Battery Grounding Cable was corroded. I changed it out ($10 at autozone) - All good now. The chassis cable was good and clean.

So - Starter was fine , Relays was fine - Ground to Engine Chassis - Not Good!

Thanks for your input!
 
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