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Discussion Starter #1 (Edited)
I've finally traced back my parasitic amp draw to the white Molex input on my radio unit (2nd from the left):


It's pulling about a 300mA draw and killing my battery. I've found some replacement units online for around $200, but I would prefer to trouble shoot it even further and possibly try to fix the unit myself somehow. However, I can't seem to find any schematics out there for the unit that would help me with that. And even if I found it, I'm not sure I would know exactly where to start. Also, the unit itself may be fine. It may actually be whatever plugs into the other end of that wiring harness, but again I don't have any diagrams that show me that.

Does anyone have any suggestions for how to troubleshoot this issue myself any further?

Thanks!

Here are some more photos and the info on the unit:


 

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Question: how did you measure current from the factory head? That method matters to an accurate diagnosis.
 

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Discussion Starter #3 (Edited)
Question: how did you measure current from the factory head? That method matters to an accurate diagnosis.
I disconnected the negative battery clamp from the terminal. Then, I measured current (using my multi meter, with doors closed and all lights off). I was consistently getting between 250mA - 350mA until I removed the fuse for the "Radio", which then showed a reading of 0.015mA. I plugged the "Radio" fuse back in, then removed the dash panel and radio unit. One by one I unplugged Molex connectors from the back, got out of the truck, closed the door, then measured current. When I unplugged the white one, the reading went back to 0.015mA. I plugged it back in and it went to 250mA - 350mA.

Is that what you are looking for?

Edit: To clarify my second sentence above, I connected my meter leads to the negative terminal and the clamp.
 

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I disconnected the negative battery clamp from the terminal. Then, I measured current (using my multi meter, with doors closed and all lights off). I was consistently getting between 250mA - 350mA until I removed the fuse for the "Radio", which then showed a reading of 0.015mA. I plugged the "Radio" fuse back in, then removed the dash panel and radio unit. One by one I unplugged Molex connectors from the back, got out of the truck, closed the door, then measured current. When I unplugged the white one, the reading went back to 0.015mA. I plugged it back in and it went to 250mA - 350mA.

Is that what you are looking for?

Edit: To clarify my second sentence above, I connected my meter leads to the negative terminal and the clamp.
That explains you procedure nicely. Good approach too!

In the absence of what is "normal", all by itself, 300mA isn't much of a concern. I'll look in FSM to see oif there is any info but I'm kinda doubting that to be the case. Another question: over what duration is this current drain "killing" your batt? If its very short, I doubt the root of the problem is this drain - but thats based in nothing more than previous troubleshooting efforts on other vehicles.
 

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Discussion Starter #5
I'll look in FSM to see oif there is any info but I'm kinda doubting that to be the case.
What is FSM?

Another question: over what duration is this current drain "killing" your batt? If its very short, I doubt the root of the problem is this drain - but thats based in nothing more than previous troubleshooting efforts on other vehicles.
If I leave it sitting for 3 days it usually needs a jump.

Also, one more clarification. When I take the reading, it usually starts pretty high around 800mA - 900mA, but then creeps down and settles in around 250mA - 350mA, but continuously changing in between those values (250 - 350). Not sure why the initial spike, but it may be a clue.
 

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What is FSM?

If I leave it sitting for 3 days it usually needs a jump.

Also, one more clarification. When I take the reading, it usually starts pretty high around 800mA - 900mA, but then creeps down and settles in around 250mA - 350mA, but continuously changing in between those values (250 - 350). Not sure why the initial spike, but it may be a clue.
FSM = Factory Service Manual

I'd volunteer to duplicate your procedure but have other things underway. There are a number of devices on board drawing current to "keep alive", so again, not knowing what norm is creates a vacuum. All things being equal, 300mA current should not be killing a healthy battery in 3 days.

Whats the age of your starting battery? Also note, pulling any liquid immersed lead plate battery below 11 VDC more than a few times starts the sulfation snowball. Once thats in play, the snowball of retaining (or lack thereof) a state of charge accelerates.
 

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Discussion Starter #7
FSM = Factory Service Manual

I'd volunteer to duplicate your procedure but have other things underway. There are a number of devices on board drawing current to "keep alive", so again, not knowing what norm is creates a vacuum. All things being equal, 300mA current should not be killing a healthy battery in 3 days.
I guess I'll never know what norm is, but I've read and seen that 50mA is the max that any vehicle should be drawing when off. This is 6 times that. In 3 days time, that's 21 amps, which may not be significant enough, but I do know that if I remove my "Radio" fuse for those 3 days (my temporary fix), my truck starts right up no problem. If I don't, it's either dead or barely turns over.

Whats the age of your starting battery? Also note, pulling any liquid immersed lead plate battery below 11 VDC more than a few times starts the sulfation snowball. Once thats in play, the snowball of retaining (or lack thereof) a state of charge accelerates.
The battery is 1 year old and measures 12.14V. In fact, I've had to replace it twice before (thankfully for free at Auto Zone) in the last 2 years, but I'd rather not keep replacing batteries. I need to find the root cause. I think I'm getting close, but I'm sort of at a dead end now not knowing how to proceed past this wiring harness/radio.
 

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I guess I'll never know what norm is, but I've read and seen that 50mA is the max that any vehicle should be drawing when off. This is 6 times that. In 3 days time, that's 21 amps, which may not be significant enough, but I do know that if I remove my "Radio" fuse for those 3 days (my temporary fix), my truck starts right up no problem. If I don't, it's either dead or barely turns over.

The battery is 1 year old and measures 12.14V. In fact, I've had to replace it twice before (thankfully for free at Auto Zone) in the last 2 years, but I'd rather not keep replacing batteries. I need to find the root cause. I think I'm getting close, but I'm sort of at a dead end now not knowing how to proceed past this wiring harness/radio.
Matchless, a quick search of the FSM didn't return info on "normal" battery drain with vehicle at rest. Note this text from section 4-24 "Symptom Troubleshooting Index":

"Check for excessive parasitic electrical current draw with the ignition switch OFF, and the key removed. The multiplex control unit may take up to 10 minutes to turn off (sleepmode)for some models."

Sounds like you may have done google searches on battery drain symptoms. 12.41V measured after vehicle at rest for a bit, like 15 minutes or so? Safe assumption you've ruled out charging related issues? No potential intermittent probs in charge circuit? All terminals in the path between batt, alternator, ETC are good? You've checked voltage inside the vehicle while underway? Have you left batt disconnected overnight or longer and measured pre/post voltage? Wonky cells can self discharge.

Personally I'm dubious of factory head unit being at fault without other symptoms but that suspicion isn't based on knowledge of the RL head. Just "feels" unrelated. RL radios have been known to do weird things.

BTW: you've employed a sound diagnosis procedure, I'm just wondering if conclusion is accurate.
 

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I guess I'll never know what norm is, but I've read and seen that 50mA is the max that any vehicle should be drawing when off. This is 6 times that. In 3 days time, that's 21 amps, which may not be significant enough, but I do know that if I remove my "Radio" fuse for those 3 days (my temporary fix), my truck starts right up no problem. If I don't, it's either dead or barely turns over.



The battery is 1 year old and measures 12.14V. In fact, I've had to replace it twice before (thankfully for free at Auto Zone) in the last 2 years, but I'd rather not keep replacing batteries. I need to find the root cause. I think I'm getting close, but I'm sort of at a dead end now not knowing how to proceed past this wiring harness/radio.

Just to be clear, 12.14 is a discharged battery. Are you reading that after sitting for a few days or right after charging?

Assuming that the charging system and battery is ok (fully charged is around 12.75 volts) then. . .If pulling the radio fuse solves the draining problem then I don't think there is much room for debate, you have isolated the troubled circuit and now need to figure out what part of it is the issue.
 

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Just to be clear, 12.14 is a discharged battery. Are you reading that after sitting for a few days or right after charging?

Assuming that the charging system and battery is ok (fully charged is around 12.75 volts) then. . .If pulling the radio fuse solves the draining problem then I don't think there is much room for debate, you have isolated the troubled circuit and now need to figure out what part of it is the issue.
Good point. 12.14 is somewhere around 50%. Assumed that was after the batt had been pulled down by the parasite.

After re-reading the OP, whatever the white plug is (changer/XM/ETC) is the likely culprit.
 

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Discussion Starter #12
12.41V measured after vehicle at rest for a bit, like 15 minutes or so?
Yes

Safe assumption you've ruled out charging related issues? No potential intermittent probs in charge circuit? All terminals in the path between batt, alternator, ETC are good?
Yes. Alternator is the only thing saving me right now.

You've checked voltage inside the vehicle while underway?
No. Not sure how to do pull that off.

Have you left batt disconnected overnight or longer and measured pre/post voltage? Wonky cells can self discharge.
No. Again though, not thinking voltage is the problem. I had the same symptoms with the previous 2 batteries.

Personally I'm dubious of factory head unit being at fault without other symptoms but that suspicion isn't based on knowledge of the RL head. Just "feels" unrelated. RL radios have been known to do weird things.
True, it might not be the head unit. It might be whatever plugs into that white Molex connector. But the problem is I don't know what that is. Does the FSM give any indication what that might be?

Just to reiterate: "Radio" fuse in = 350mA draw, slow crank every morning. "Radio" fuse out = 15mA draw, normal crank every morning. While Molex plugged into radio = 350mA draw. White Molex not plugged into radio = 15mA draw. I need to find out where the white Molex goes.

its a bit of an "eye chart" to read but this thread has a Honda Service News article on acceptable parasitic draw figures.

http://www.ridgelineownersclub.com/forums/showthread.php?t=46812&highlight=Parasitic+draw
Thanks. After reading that write up from Honda, it does state that anything less than 50mA is normal. It also states that a parasitic draw of about 200mA will usually kill a battery in about 2 days. So, I'm pretty sure this draw is what's killing my battery.

Just to be clear, 12.14 is a discharged battery. Are you reading that after sitting for a few days or right after charging?
That reading was taken this morning after the truck ran the previous day and sat overnight. Probably not a full charge. I understand the battery needs to be replaced (just like the last 2...probably as a result of this draw), and I plan to do that AFTER I figure out the cause of the draw so that I hopefully don't have to replace it a 4th time.

Assuming that the charging system and battery is ok (fully charged is around 12.75 volts) then. . .If pulling the radio fuse solves the draining problem then I don't think there is much room for debate, you have isolated the troubled circuit and now need to figure out what part of it is the issue.
Exactly! So, does anyone know what the white Molex (2nd from the left shown below) on the back of the radio head unit goes to?



 

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Hope this helps

Radio.jpg

Radio1.jpg

BTW: apologies for not paying closer attention to the issue first time around. Looks like you should be able to disconnect the external device without losing the primary head unit.

Good luck
 

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Discussion Starter #14
Hope this helps

BTW: apologies for not paying closer attention to the issue first time around. Looks like you should be able to disconnect the external device without losing the primary head unit.

Good luck
No problem. And thanks very much for the info! I actually never use the CD player/changer anyway, so I'll give that a shot and see how it goes. Thanks again!
 

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Discussion Starter #15
Just curious though...if I still wanted/needed to use the cd changer, could I somehow re-route the power wire (purple) to another power source that would only work when the truck is on?
 

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Without looking at the FSM, if it was me I'd be looking into which relay powers the CD changer circuit. If the RELAY is bad and stuck closed, the circuit would remain hot when it should "OPEN" there by disconnecting the changer or XM unit. (Someone stated CD changer, diagram calls it XM?).

Another thought if that goes to a CD Changer, XM unit or ????, you may be able to check on disconnecting at that item? If I remember correctly the XM is behind the back seat, and the Navi DVD is under a front seat(unsure which one) and I'm unsure where a CD changer is or could be.

Like I said, If it were me I'd be checking the FSM, for which Radio, XM, CD Changer, or NAVI DVD drive unit are tied into which Relay(s) and either buy one or start swapping them around(swap like size relays or you will have a real mess)
 

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According to this article from Honda Service News, 25mA or less is considered normal. Anything more is excessive parasitic draw.

 
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