Acura MDX SUV Forums banner

1 - 20 of 21 Posts

·
Registered
Joined
·
9 Posts
Discussion Starter #1
Hello, I am trying to solve an issue with my wipers on a 2004 MDX with nav and auto rain sensing.

They are not working on Auto/Low/Intermittent, but OK on high. They also do not "park" properly and stop at whatever point the switch is turned off.
Many other posts suggested replacing the wiper control but unfortunately that didn't fix it.

When I turn the wiper control from OFF to AUTO, I hear a clicking noise coming from somewhere behind the washer fluid reservoir. So, I opened a small box of relays underneath and am wondering if one of these is the automatic wiper relay? I've attached a photo and circled the relays, but can't find them labelled anywhere in the user's manual.

Does anyone know what these relays are?
Many thanks
 

Attachments

·
Registered
Joined
·
591 Posts
Factory manual shows that in your picture, the top left is the intermittent wiper relay and top right is the automatic wiper relay. If you know you have two good ones of the same style/model from another location, you could swap them one at a time and see if the problem resolves or the problem "moves" with the relay. Can't say for sure but the one in the lower right looks like a candidate to try swapping.

If you can't hear exactly which relay is operating, you could have a helper turn the wiper on high while touching the relay housing to feel which one is actually clicking. My guess is the automatic is working.

You might also want to check the driver's side fuse box for a blown 10A fuse that feeds the intermittent wiper circuit. It's supposed to be no. 11. If you can't find no. 11, you could check or switch the 10A fuses you find.

There is also a 7.5A fuse that feeds the rain sensor. No. 91 in aux fuse holder.

Good luck!
 

·
Registered
Joined
·
9 Posts
Discussion Starter #3
Thanks kindly!

I have swapped the relays in various ways and the problem doesn't move, also all of the fuses mentioned are testing OK.
(On a side note... MAN are those auxiliary fuses hard to reach!! But I found the 7.5A to be good)

I just disconnected the plug from the wiper motor and am just searching out some wiring diagrams to check the circuits from the control switch to the plug... if everything looks good I will probably replace the wiper motor at this point.
 

·
Registered
Joined
·
591 Posts
Maybe this might help you narrow down the cause to wiring or motor. To one of your original points about the wipers not parking, a Haynes manual for the Pilot/MDX states to turn the wipers off, then key on and look for battery voltage at the green/black wire feeding the wiper motor. Btw, that wire comes from a 30 amp fuse (#12) in the driver's side fusebox.

If you need a manual, Belairbrian posted this link which is a great deal for a factory manual.

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

Haynes manuals are pretty inexpensive - about $20 local parts store, even less online.

Good luck!
 

·
Registered
Joined
·
9 Posts
Discussion Starter #5
Thanks again, interesting stuff

Measuring the green/black wire from wiper plug to ground is indicating 5.25V with key on and wipers off. I tried all wiper settings and the green/black always reads 5.25V. However, I am reading 11.77V at the 30A fuse labeled FR WIPERS and fuse tests OK... I wonder if should I be getting the same 11.77V at the green/black?
 

·
Registered
Joined
·
1,725 Posts
There is nothing but a wire and a connector or two between fuse #12 and the green/black wire at the wiper motor, so if you're not getting full battery voltage there, there's an open connection (which is probably good news because fixing a broken wire is usually cheaper and easier than replacing wiper motors). ;-) Just start tracing that green/black wire back from the wiper motor toward the fusebox and figure out where the voltage disappears, and you will have found your problem.
 

·
Registered
Joined
·
591 Posts
You could try wiring the green/black directly from the 30A fuse and see if the park and slower speed wiper functions are restored. It would also confirm if that leg of the wiring is the cause.
 

·
Registered
Joined
·
591 Posts
Looks like the green/black has a branch or branches that feed the coil side of the auto and intermittent relays in you OP. So you should be getting battery voltage there too. Not sure if this would work or help but it might be worth removing the relays with key off, then key on and checking for battery voltage at the wiper motor again. Then with key off, plug one relay back in at a time and check the voltage at the wiper motor each time. Mentioning this in case the relay is causing the voltage drop. However, you mentioned swapping relays didn't do anything so maybe this won't reveal anything new.

Anyways good luck!
 

·
Registered
Joined
·
9 Posts
Discussion Starter #9
Man, so sorry... I've been re-checking voltages tonight and now I get green/blk reading 12V from fuse to wiper motor plug. Must have had the wrong pin at some point, my apologies!

I've attached some photos with the specific voltage readings I've been getting, for further clarification. I tested all the relays (Mitsuba RC-5101) with a separate 12V power source and they all clicked and bridged to other pins (in identical fashion) so they appear OK. My wiring diagram doesn't give the specific pin layout, so I've just labeled the voltage at each connector, looking for anything suspicious.

POSSIBLE ISSUES?

1. Intermittent relay actually clicks TWICE (and sometimes three or four times) when I turn the wiper switch from OFF to AUTO
2. Reading approx. 2V on intermittent relay on the middle pin (I believe this is pin#4, blue/white)... fluctuates slightly from 1.8 to 2.3V
3. The "Unknown Relay" has 12V and 10.9V coming into pins 3 and 5, this is very different than the other 2 relays! I'm wondering what this relay is all about... I only happened to check it because it was in the neighbourhood
4. Wiper motor plug reads the same constant voltage on all wiper switch settings (OFF/AUTO/LOW/HIGH) and there is a constant 4.95V on the blue/white

Anyhow... I'll certainly keep poking around and update with any progress.
Thanks a ton for any thoughts!
 

Attachments

·
Registered
Joined
·
1,725 Posts
Seems to me that you should have voltage on the normally closed "output" side of the Intermittent Wiper Relay (pin 4). I believe that this is fed from the wiper motor itself, though I'm having no luck finding more info on exactly how this is supposed to work. In short, the power comes into the wiper motor on the green/black wire, and comes OUT of the wiper motor on the blue/white wire, feeding the intermittent wiper relay and control unit. I'd suggest monitoring the power on the blue/white wire and see what it does.

FYI, the pin-out for the SPDT (Singe Pole, Double Throw) relays is here:


It's also significant that the wiring diagram for the wipers is very different if your MDX has automatic (rain-operated) wipers. Please confirm this is the case (I'm guessing so based on the fact you do have a relay in the automatic wiper position).

And finally, I'm sorta / kinda convinced that the parking mechanism is inside the motor itself, with the ground (via the black wire to the motor) supplying a circuit that applies ground to the motor any time it's NOT in the parked position (which means it's GOT to run until it's parked).

Also, there is a separate low and high speed ground input to the motor, so a failure in the low speed circuit would also cause most of the problems you're having.

The short version: 90% you need a new wiper motor.
 

·
Registered
Joined
·
591 Posts
One item that gives me pause is that you mentioned the relay clicks several times. If that is relay chatter, that could be a loose connection/wire in the system or the motor is going/gone.

If you have alligator clips, with wipers off, key off, you could connect 12V to the motor where the grn/blk would enter and ground the motor where the black would enter. After making sure your connected good and no shorts, turn key on (wipers off) and see if the wipers park.

I recall there is also a test where you can connect power and ground to the different pins. I’ll see if I can find it.

FWIW, a motor on rockauto is about $65. I’m leaning towards a motor too but maybe a little more checking first.

Glad to see your patient and persistent!
 

·
Registered
Joined
·
9 Posts
Discussion Starter #12
It's also significant that the wiring diagram for the wipers is very different if your MDX has automatic (rain-operated) wipers. Please confirm this is the case (I'm guessing so based on the fact you do have a relay in the automatic wiper position).
You betcha, this is the auto rain sensing version.
 

·
Registered
Joined
·
9 Posts
Discussion Starter #13
Thanks everyone, really appreciate all that info
Well, after work today I swapped in a wiper motor from a 2003 Honda Pilot that I found at salvage that had identical part/model numbers on the label, but unfortunately there was no change in behaviour. Worked in HIGH only. Not sure what the chances of 2 faulty wiper motors are, but hey, for $25 I played the odds :)

I'm going to follow that blue/white wire voltage and see what I can learn, and test/confirm habbyguy's relay diagram to the ones currently installed. Also will do the alligator clips from LeftOverParts suggestion and post any results ASAP
 

·
Registered
Joined
·
1,725 Posts
Sorry to hear that the new motor didn't cure the problem. That means (I think...) that you're not getting a ground to the blue wire going to the motor. Try grounding that, and the motor should run on low speed (and I suppose, park properly, though there's nothing in the manual that specifies which "speed" circuit the motor uses to park).

From there, it looks like the ground comes via a gray wire running to the wiper switch, which is supplied the ground via a white wire running to the intermittent wiper relay. That relay seems to switch the white wire to ground when the relay is energized, and to 12 volts when it isn't, sourced through fuse #91, supplied by the automatic wiper control unit. Or not... take that with a grain of salt...

I found a troubleshooting process for the automatic wiper module - it may well help...




Here's the circuit diagram for the model WITH automatic wipers (very different from the "regular model" like mine)... ;-) It's split into two pages - you have to imagine them connected.

 

·
Registered
Joined
·
591 Posts
You mentioned the blue/wht was reading <12V and the test table shows that it should be either 0 or 12V depending on the switch setting.

From the diagram, looks like there are grounds at the intermittent relay and intermittent control. (Plus others.)

Not sure if the relay ground terminates here but there is a large bundle of grounds on the fender behind the washer fluid holder. I recall mine being built up with the usual engine compartment grime. You might want to check that. (You could also run a separate ground.)

Saying the above because of the mentioning of what might be relay chatter and the motor is ruled out. Im wondering if you live in cold/wet area, if the wipers are used a lot (as opposed to So Cal) if your relay contacts could just be worn. I know you swapped them and didn’t see a difference. Not saying to go buy one but maybe google, how to test a 12V relay, and test them out of the X. Check if 12V will go through when you energize the relay. Trying to think through what might cause the relay to bounce.

(The motor test diagram is what I was referring to earlier. Like your junker motor, I plan to do a similar test with a junker accelerator pedal sensor for a Mazda. $17 vs $129.)

Good luck!
 

·
Registered
Joined
·
9 Posts
Discussion Starter #16
MANY THANKS
Those diagrams are golden!

-I checked and cleaned up that nest of grounds behind the washer fluid and they all have good continuity to ground, I'm pretty sure they are OK
-I tested the relays out of the vehicle with a good second 12V battery, all checked out OK
-Motor tested OK and the low speed worked flawlessly when I grounded Blue and supplied 12V to Grn/Blk... that was a nice feeling actually :)

So... here are my control unit test results! Blue/White again is crying out for help. Something is not happy on that circuit. I can almost see the nibble marks in my mind... I'll do some careful probing in the next few days and see if I find anything.

But also in that test, although there was continuity on the GRN/YEL to Ground, there were 2 ohms of resistance, not what I was expecting... would you guys consider that a "test failed" in this setup?
 

Attachments

·
Registered
Joined
·
1,725 Posts
Good stuff... I love data! ;-)

The constant 4 volts on the blue/white line sure doesn't sound right (or indicates the problem lives there). Are you using an analog meter? They say that's a necessity, but I'd have to believe that even with a digital meter (even a cheap one) you'd see the voltage fluctuating. I looked at that circuit and (and this is important) assuming the wiper switch is on low as specified in the procedure, the white wire is effectively disconnected, so the only voltage on the blue/white has to be coming from the wiper motor (which you've swapped) or the automatic wiper control unit. It's hard to say which is the input and which is the output, but the troubleshooting process doesn't list the control unit as a possible solution to this voltage being wrong, though it does list fuse #91 (which you previously checked and pronounced OK). Might be worth double-checking that fuse (make sure the voltage on both sides is exactly the same). I wish Honda put some more info on how that circuit actually works - the "schematic" of the motor looks more like a pie chart than a schematic... ;-)

Connecting the green/red to ground causes a relay to click, which it should (the intermittent wiper relay). I'm betting you still have the wiper switch set to "low" - I'll bet if you turn it to off and re-test, the test will work (the wipers will run on low). That's because the intermittent wiper relay closing applies a ground to the white wire, which is connected through the wiper switch (but only when in off or intermittent) to the gray wire, and then through the automatic wiper relay in its "unpowered state", then onto the wiper motor's low speed ground connection.

I have no answer on the green/yellow resistance - 2 ohms is likely OK (doesn't appear to be a "power circuit", so it would seem that 2 ohms would be capable of pulling any "signal voltage" to ground.
 

·
Registered
Joined
·
591 Posts
Great testing and glad to see you narrowing it down!

Thinking 2 ohms on grn/yel is nothing to be concerned with and focus should be (at least first) on what’s causing the 4V on blue/wht.

From your test results, looks like you never got 0V or 12V for blue/wht and it was always 4V. Theres the male and female connector at the rain sensor you could check for 4V. You could do the same for intermittent control. (Another one to check is what happens to 4V when you pull the 7.5A fuse going to the rain sensor).

If neither device is supplying the 4V and it’s wiring, you could try bypassing the blue/wht wire runs with a new wire (again one at a time.)

You mentioned you replaced the wiper switch - wondering if white low speed wire could have a role. You’d have to check for voltage or continuity at the column and to the intermittent relay.

Well, you’re getting close! Nice work so far!
 

·
Registered
Joined
·
9 Posts
Discussion Starter #19
Yes, I actually splurged the $15 and did the "official" analog test -- I must be getting desperate :D

So, quick question... this morning I added some 12" leads to the intermittent relay so I could tap into the live pins while switching to different settings. With the key ON and wiper switch OFF, I'm getting full continuity on the intermittent relay between PIN 1 and 4 (white --> blue/white), AND SIMULTANEOUSLY PIN 1 and 2 (white --> black/ground #201). Isn't that what this relay is preventing?

(When I disconnect my PIN 4 (blue/white) connector from the relay, PIN 1-->2 loses continuity!)
 

·
Registered
Joined
·
591 Posts
I pulled the intermittent relay, hooked up 12V and got the same results. NO/NC operated as expected. Picture has the notes.

I noticed my relays are clocked 180 degrees from yours. In my 06, the wiper relays are the two nearest the radiator. The second picture shows the relay box and ground bundle for orientation.

In case it helps, I also pulled each wiper relay and then with key On in position II, cycled the wiper switch to see what would happen. (Works correctly with both installed.) Results are in the picture. I must admit, I didn’t expect some of the results. Shows my limitation on reading the diagram.

Good luck!
 

Attachments

1 - 20 of 21 Posts
Top