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Old 07-23-2010, 01:46 PM
DrummerBoy523 DrummerBoy523 is offline
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Question Anybody replace the on board computer

Anybody ever replaced the on-board computer themselves? I've got a 2000 EX-L 4 Cyl. The OBC is shot - my door locks wont work, my dash lights are freaking out - you name it. The CE light came on and the dealer told me (for $100) that it was the OBC and he quoted me $1100. Ugh. Any tips, suggestions, advice is appreciated.
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Old 07-23-2010, 02:55 PM
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Your dash lights and door locks have nothing to do with the PCM. The PCM only controls the engine and transmission.

The MICU, or multiplex control units, operate the door locks and dash lights (back lighting).

If the PCM needs replacement, it has to be programmed by Honda or someone with a Honda HDS for your keys otherwise it won't run.

What codes did they get out of the car for the check engine light?
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Old 07-23-2010, 06:44 PM
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Quote:
Originally Posted by Fredsvt View Post
Your dash lights and door locks have nothing to do with the PCM. The PCM only controls the engine and transmission.

The MICU, or multiplex control units, operate the door locks and dash lights (back lighting).

If the PCM needs replacement, it has to be programmed by Honda or someone with a Honda HDS for your keys otherwise it won't run.

What codes did they get out of the car for the check engine light?
From the invoice, I see something that looks like a code:
P0560 VBU Signal Failure

They also mention there is No Power on #13 Clock and Back up Fuse.

They recommend ECU 37820-PAA-L94 for $1020.00

Thoughts?
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Old 07-23-2010, 07:17 PM
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Bruce Hawkins Bruce Hawkins is offline
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Did you Check fuse 13?
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Old 07-23-2010, 07:22 PM
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Did you Check fuse 13?
I didn't check the fuse - I figured that would be the first thing the mechanic would check since I mentioned it to them when I brought it in. I guess we all know what happens when one assumes, don't we? I'll have to check the fuse in the morning - but I'm guessing a blown fuse wouldn't cause the CEL to come on.
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Old 07-24-2010, 10:44 AM
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The code you posted is a system voltage out of range code.

The part they want to change is the PCM. I think the grand they want is including labor and the part. But why they'd be changing the PCM, for a fuse that's dead is beyond me.

The PCM doesn't control or power any fuses itself.

I'm going to have to look into this further once I start up my laptop today so I can get onto Honda's site to look this up.

If in fact the "backup" and clock fuse doesn't have power, you should have an inoperative clock AND radio, along with the PCM constantly losing it's retained memory.

I'd be starting at that problem before anything else.
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Old 07-24-2010, 11:15 AM
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Quote:
Originally Posted by Fredsvt View Post
The code you posted is a system voltage out of range code.

The part they want to change is the PCM. I think the grand they want is including labor and the part. But why they'd be changing the PCM, for a fuse that's dead is beyond me.

The PCM doesn't control or power any fuses itself.

I'm going to have to look into this further once I start up my laptop today so I can get onto Honda's site to look this up.

If in fact the "backup" and clock fuse doesn't have power, you should have an inoperative clock AND radio, along with the PCM constantly losing it's retained memory.

I'd be starting at that problem before anything else.
If it might help - I've installed an aftermarket CD Changer for my iPod (USA Spec adapter: http://tinyurl.com/2afvw4k. I did this over a year ago - so I don't think this has anything to do with this problem but you never know.

I've got power to the radio, so the circuit is complete. If I recall, if I unhook the clock, the radio and other things quit working on the dash - this happened when I installed the USA Spec adapter and forgot to hook the clock back up. Once the clock was hooked then everything worked again.

So far, the troubles that I've got are: The door locks only work when the ignition is on. Usually, they work anytime. Also, the interior lights are out along with the clock. I've not noticed anything else.

I googled the part number 37820-PAA-L94 and found that it is the ECU (Engine Control Unit?). http://tinyurl.com/29ucajx

Let me know what you find out because if this is something that I can do myself (I'm fairly handy) and save $500, then by all means I will attempt to do it. But, I don't want to drop $500 on something that I don't need either (duh).

Thanks so much for your continued help.
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Old 07-24-2010, 12:59 PM
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You can't replace the car's PCM (ecu as you call it), without being able to program the keys to it. You can put it in, but the car won't run.

The PCM (powertrain control module) has NOTHING to do with door locks or interior lights Do you mean dome lights or do you mean the cluster and control back lighting?

If you hooked the factory illumination wiring to the aftermarket radio, more than likely you've smoked the left side multiplex control unit. The factory illumination wiring is a pair of network data lines that do nothing more than tell the back lighting how bright or dim to go. Nothing can be hooked to these wires other than the factory radio, unless the aftermarket radio is designed to operate with the car's multiplex network.

In order to get the night time illumination on your aftermarket radio, you need to locate the power wire that goes to the glove box light and tap into that, as that's a controlled power, not a controlling communication line. The MICU boxes don't have any protection for shorted to ground or shorted to power of the data lines, and thus they go up in smoke internally when something like that happens.

The clock being unplugged should have nothing to do with the radio or door locks.

You may have to temporarily unhook the radio, and put the clock in, and see what works or not. You also need to go over all the fuses, under hood, left side and right side of dash to make sure they are all good.

There is also a way to "reset" the door locks, but what you're describing doesn't sound like that's the issue.
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Old 07-24-2010, 01:09 PM
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Double Check fuse #13 and also #9 in the drivers side panel. It also feeds the clock light circuit and is only powered on with the ignition. Which may explain why you door locks only work with the ignition on.
I would suggest checking the clock electrical connectors to be sure they are clean and fully seated. The drivers side multiplex unit is fed thru the clock connector (pins 3&4). If fuse #13 is good you may want to verify power is getting to the clock connector. Pin 2 - white/yellow wire should have 12 volts all the time.

If these things are ok, you may want to try a different (used?) clock as the intenal electronics might be messing up the multiplexer.

Good Luck
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Old 07-24-2010, 01:40 PM
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Did the shop clear the P0560 code? Or is the light still on?

The code refers to the backup circuit to the PCM receiving 6 volts or less for 2 seconds while the car is operating.

Checking that there is power going into and out of the "backup" fuse is important. If there is power coming out of the under hood box, you then need to go to the PCM to check for power there. The wire is in connector B number 21, should be a white wire with a yellow tracer on it.
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Old 07-24-2010, 07:30 PM
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Quote:
Originally Posted by Fredsvt View Post
You can't replace the car's PCM (ecu as you call it), without being able to program the keys to it. You can put it in, but the car won't run.
Just to be clear - I have no idea what I'm talking about. I don't call it the ECU, they are calling it that and so is every part shop that I've checked online.

Quote:
Originally Posted by Fredsvt View Post
The PCM (powertrain control module) has NOTHING to do with door locks or interior lights Do you mean dome lights or do you mean the cluster and control back lighting?
Dome lights.

Quote:
Originally Posted by Fredsvt View Post
If you hooked the factory illumination wiring to the aftermarket radio, more than likely you've smoked the left side multiplex control unit. The factory illumination wiring is a pair of network data lines that do nothing more than tell the back lighting how bright or dim to go. Nothing can be hooked to these wires other than the factory radio, unless the aftermarket radio is designed to operate with the car's multiplex network.
The only thing I did was to hookup the USA Spec adapter to the CD Changer hookup on the factory radio. The USA Spec module gives the ability to play your iPod through the factory radio's CD Changer interface. The USA Spec module gets its power from the radio. That is all that I did.

Quote:
Originally Posted by Fredsvt View Post
Did the shop clear the P0560 code? Or is the light still on?
CEL still on.

Quote:
Originally Posted by Fredsvt View Post
The code refers to the backup circuit to the PCM receiving 6 volts or less for 2 seconds while the car is operating.

Checking that there is power going into and out of the "backup" fuse is important. If there is power coming out of the under hood box, you then need to go to the PCM to check for power there. The wire is in connector B number 21, should be a white wire with a yellow tracer on it.
Not exactly sure what/how to do what you are saying I should do. What fuse is the "backup" fuse - is that #13? And, I wouldn't have a clue as to how to check for power on the PCM - I don't even know where it is.

Thanks again for your continued help!
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Old 07-24-2010, 07:31 PM
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Quote:
Originally Posted by nehonda View Post
Double Check fuse #13 and also #9 in the drivers side panel. It also feeds the clock light circuit and is only powered on with the ignition. Which may explain why you door locks only work with the ignition on.
I would suggest checking the clock electrical connectors to be sure they are clean and fully seated. The drivers side multiplex unit is fed thru the clock connector (pins 3&4). If fuse #13 is good you may want to verify power is getting to the clock connector. Pin 2 - white/yellow wire should have 12 volts all the time.

If these things are ok, you may want to try a different (used?) clock as the intenal electronics might be messing up the multiplexer.

Good Luck
Thank you - My dad (the electrician in the family) is going to be visiting this weekend and I'll have him help me check the fuses and the clock connectors.
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Old 07-25-2010, 08:25 AM
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The PCM is located on top of the tunnel, forward of the console.

The "backup" fuse is located in the underhood fuse box, marked "backup" usually.

The dome lights also go through the multiplex unit for the dim to off when you close the door. Does the small light on the door panel itself come on when you open the door?

I think you can safely eliminate any issues with the radio, as long as the back lighting works.

I think the dealer wants to change the PCM because of the code, provided they did the proper testing to determine that there is actually power at connector b terminal 21. The PCM won't make any change to your dome light issue.

I'll have to look up to see what fuse 13 does.
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Old 07-25-2010, 12:54 PM
DrummerBoy523 DrummerBoy523 is offline
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Quote:
Originally Posted by Fredsvt View Post
The PCM is located on top of the tunnel, forward of the console.

The "backup" fuse is located in the underhood fuse box, marked "backup" usually.
I looked in the underhood box - but didn't see anything that stood out as a backup fuse. I'll have to look again.

Quote:
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The dome lights also go through the multiplex unit for the dim to off when you close the door. Does the small light on the door panel itself come on when you open the door?
Yes, the small light comes on.

Quote:
Originally Posted by Fredsvt View Post
I think you can safely eliminate any issues with the radio, as long as the back lighting works.
Backlighting comes on. I don't this this is an issue w/radio - agreed.

Quote:
Originally Posted by Fredsvt View Post
I think the dealer wants to change the PCM because of the code, provided they did the proper testing to determine that there is actually power at connector b terminal 21. The PCM won't make any change to your dome light issue.
I just checked the dome light - and it appears to be working - not sure what I saw the first time around, but we can eliminate that.

Quote:
Originally Posted by Fredsvt View Post
I'll have to look up to see what fuse 13 does.
So, here is what I have so far:
  • CEL light is on with a code of P0560 (VBU Signal Failure). The notes on my invoice say "no power on #13 Clock and Back Up Fuse"
  • Clock is out.
  • Windows (except for driver's side) wont work from driver's panel.
  • Locks from key FOB dont work. Only work with ignition on and door closed (can lock/unlock).
  • I checked fuse #13 and it looks fine to me.
  • I looked in the underhood compartment and dont see a backup fuse - not sure which fuse is the backup.

I'm not sure what I need to be doing with connector b terminal 21 or where this even is. Please expand further..

Quote:
Originally Posted by Fredsvt View Post
The PCM is located on top of the tunnel, forward of the console.
I'm still not for sure where the PCM is. Do you mean under the radio? Not sure what you mean by "tunnel"?

Again, thanks for your help. I am not sure what I need to do at this point, so any further explanation would help. I'm far from a car mechanic, but am able to do a lot of stuff myself and am willing to learn.
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Old 07-25-2010, 04:32 PM
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Apologies, the "backup" fuse that they are looking at is NOT in the under hood box.

The PCM is near the firewall, on the floor (the raised part between the seats) in front of the console. Before we get to the PCM we need to know if there actually is power going into and out of fuse 13.

Even though the fuse is good, if there's no power at the feed side, then there's another issue. If you can get a plain old 12v test light, hook the clamp to a good clean ground on the car. Then touch the probe to the metal exposed part of the fuse while its in the box, if it lights up, on both parts of the fuse, it's good. If it doesn't on one side but on the other the fuse is bad.

Check fuse 54 in the under hood box, is it good? This feeds fuses 9 to 13 in the right side fuse box. I'm going to guess it is.

From what I can see, ALL the issues you have are related, the locks, windows, remotes, security and part of the climate control won't work properly.

I have suspicions of what may be wrong, but I need to know whether fuse 13 has power in and out first, then we can go from there.
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Vermilion 1999 SVT F150 Lightning, Sylvania/Visteon Xenarc HID headlamps, '01 L turn/marker lamps, PIAA fogs, '01 up Bilstein shocks, all Pioneer speakers, Clarion subwoofer. All Redline fluids.

Silverstone 2003 Honda S2000, bone stock
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