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Ground 302

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6.1K views 23 replies 4 participants last post by  davedrivesody  
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#1 ·
Hey guys. Got an abs and tcs light on last week. Was intermittent and now solid. Went off once today, but back on.

Codes are: 51-01 Abs pump motor failure
53-01: abs motor relay short

Now, before i go ahead and replace the pump, i tried to do some troubleshooting. Various forums said to check continuity of pins 24 and 25 on the abs module to ground 302. I tried this, and did not get any continuity to any ground.

My next step is to find the ground 302 and clean it to possibly resolve my issue before i jump to replacing the pump.

Could someone tell me where the ground 302, apparently the ground for the abs pump/modulator is located on my 2004 odyssey as i have not found much good info on its location.

Thanks!
 
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#2 ·
G302 is the ground for the ABS pump.but the ABS controller is not grounded there or anywhere else.

Test for ground from the 2P connector on the ABS pump. Pin 1 white/blue goes to the ABS pump motor relay and so should test open (with the engine off) and 12V with the engine on. The other (pin 16 oddly) black should have continuity to ground.

G302 is a bolt into a vertical painted surface, facing the front, located beside the air cleaner housing, looks like maybe two inches below the air intake tube where it enters the air cleaner housing. (Going by a photo in the shop manual here.)

If the ground checks out, the ABS pump motor relay may be bad. (See 12V test on pin 1 above.)

Dave
 
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#4 ·
Correct me if im wrong, but i just had a look under the hood. Is that ground 302? Just behind the air intake under that bracket?.

Ill clean er up once i get home from work today and see what happens.
153127
 
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#5 ·
Yep, that's it!
 
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#6 ·
Thanks! So this morning the lights turned off themselves after in started driving and remained off the entire work day. Got home, cleaned the ground real good.

Took it for a spin, no lights. Did a little burnout on some snow and the pump ran for half a second and my lights came back on solid.

Im pretty sure its the pump now, but any further diag i could do?

Also, im probably going to try and find a used pump. I read some info that it may need to be reprogrammed by the dealer? Any way to avoid that? I think my van is an ex model 2004. If i get one from an ex model, 1999-2004, could i avoid reprogramming?

Thanks
 
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#7 ·
It could be the pump alright, but might not be.

The ABS system stores a code when a failure is detected. A quick trip to the dealer to retrieve the code might save you replacing parts unnecessarily, or confirm that the part needs replacing.

BTW, it's the same pump for all Gen 2 Odyssey's.

Also, the shop manual says that replacing the pump (modulator) is just the obvious mechanical steps. There's no mention of re-programming anything.
 
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#9 ·
Yup fluid levels good, no leaks. I already pulled the codes, as per my first post, unless there is another set of codes im missing or something.

53-01, and 51-01: Abs pump motor relay short circuit, and abs pump motor failure.
 
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#10 ·
So you did!

Be sure to let us know how it goes.
 
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#12 ·
So a bit of a weird thing happened today. This is my work service vehicle so it gets used a lot with multiple startups today. Well, after a weekend of being parked, i started it this morning and the dash tcs and abs lights were not there.

Its slippery so i purposefully engaged the abs a few times, and lo and behold the pump actually worked.

Near the end of the day, i had a snowy hill to climb and there was lots of wheel slippage and tcs engaging. Got to the top and my warning lights came back on.

I assume they're the same codes but ill scan again tomorrow with my scan tool.

Im getting more and more confused haha. Kind of regret ordering the abs pump on ebay, because it seems to work still. But, i am not ruling out a bad pump yet
 
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#13 ·
So a bit of a weird thing happened today. This is my work service vehicle so it gets used a lot with multiple startups today. Well, after a weekend of being parked, i started it this morning and the dash tcs and abs lights were not there.

Its slippery so i purposefully engaged the abs a few times, and lo and behold the pump actually worked.

Near the end of the day, i had a snowy hill to climb and there was lots of wheel slippage and tcs engaging. Got to the top and my warning lights came back on.

I assume they're the same codes but ill scan again tomorrow with my scan tool.

Im getting more and more confused haha. Kind of regret ordering the abs pump on ebay, because it seems to work still. But, i am not ruling out a bad pump yet
 
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#16 ·
Not sure about a fluid change. We've owned the van for 4 yrs and have not done a brake fluid change. Im pulling it into the garage for an oil change in the next few days and ill take care of the brake fluid as well.

I have also not performed a steering angle reset. Anyone know the steps for doing so?

Thanks
 
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#17 ·
Your Gen 2 (1999-2004) does not have a steering angle sensor. It's part of VSA (vehicle stability assist), a system that I think was introduced in the Odyssey in 2005.

It's odd that ABS and TCS seem to work normally, at least for a brief period. Having little intuition about this system, I would defer to the codes and continue with the pump replacement.

Excellent suggestion above about the brake fluid. Old fluid can definitely impact the ABS modulator valves. If this is the case, I'm not sure if a brake fluid flush will fix it. But changing it is a good step anyway since it's at least 4 years old.
 
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#18 ·
Yeah i figured that. Once the pump comes in im just going to swap it out and flush out all the old brake fluid as well. Ill keep the post updated once i complete the job.

Thanks for all the help!
 
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#19 ·
Attempted to swap the abs pump this past weekend. The nuts ontop of the pump were absolutely seized. Soaked in pb blaster for 2 days and then tried using some heat with a small torch. No luck.

Anyone got any tips? Thanks
 
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#20 ·
Tap the fittings sharply with a steel hammer to a steel punch. The shock waves may help loosen the bond between the fitting and the pump.

Are you using a flare nut wrench for maximum torque? An open end wrench may slip and round the fitting.
 
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#21 ·
Thanks. If i feel like tackling it again, ill give that a try. Yes i was using a flare nut wrench. They were seized pretty good.

Its very strange because my abs and tcs worked for about an hour yesterday. Next time i started the van, it decided to quit again. I may try flushing the brake fluid first as an attempt to clean out the system.
 
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#22 ·
Figured id give a tiny update. We ended up buying a 2012 odyssey so this one is going up for sale once we get the new one on the road.

One day taking the Jeremy Clarkson approach to vehicle repair, i tapped on the abs pump with a hammer and screwdriver and lo and behold the lights turned off. If the pump kicks on, it may work a few times before the lights come back.

Tapping it will make the lights disappear. So it seems the pump is indeed the culprit. But since we are now selling the van, i wont be swapping it out. Thought id just update the thread.
 
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#24 ·
Can you sell it with the ABS/TCS lights on?

I don't think it would pass the required pre-sale safety inspection in my province.
 
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