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voltage spike 2000 LX Accord need ICU info


asilomar244
01-27-2006, 06:36 PM
Electrical problems with my 2000 LX 2.3L. SRS, ABS, MIL, door/trunk/brake lamp, battery indicators started coming on in the evening. In the morning the battery was completely dead, no relay clicks or anything. Jumped it, as soon as I started it both rear windows went down and stopped working. Replaced both window fuses, both blew again when key was turned to ign (II). Car running so I dropped it off at a local guy who has been okay for diagnostics and complex stuff before. Called back, alternator’s voltage regulator bad, and the car’s voltage spiked. His mentioned having possibly fried the ICU? I can’t find any good info on this online, and need to know more about these units. I have a shop manual on the way to help figure out the diagnostics on this and have some other options lined up since the estimate at the shop obviously isn’t feasible.

Anyone who can give some info on the ICU or which electronic components I can expect to be fried from this voltage spike and diagnostic tips for checking out the system. I’m getting the alternator tomorrow and will have the car back Monday morning. Thanks.

superbluecivicsi
01-28-2006, 01:40 AM
if your ecu is fried, you will throw a cel, start with that after the alternator install.

acurac27a
01-29-2006, 02:11 AM
yea you must mean ECU because i dont think there is a such thing as a ICU
when your ecu goes it shouldnt do anything to your windows. ECU's (engine control unit) are usually only used for electronics under the hood like opening egr valves, timing advance, fuel pressure, injector timing, ect.. it doesnt have anything to do with your windows..

i'd say you have a hot wire touching a ground somewhere, I've seen some window problems like you describe before at the wiring that goes into the door. I've usually only seen it in cars that are 10+ years old but it could be bad engineering or possibly bad wheather conditions or constant use.
after a while the wires can break from opening and shutting the door and a hot wire can possibly touch the frame of the car closing the circut and making your windows either move on their own or not move at all. If there is a positive wire touching a ground it can kill your battery after a while if it doesnt burn out whatever its connected to (window regulator). I suggest you pull the fuses out for the windows untill your sure whats wrong cause you'll probably just keep burning regulators, melting wiring. the whole dash light thing doesnt go along with this though so maybe you have some melted or exposed wiring somewhere else?

Have you had any recent engine work done before this happened or did anything under the hood or inside the dash like installed a cd deck or anything? I'm wondering if some wiring was damaged some how? I guess if the alternators voltage regulator was bad it could do this but i've never seen it happen before. Maybe your alternator could be controlled by the ECU but i've never seen that before either.

asilomar244
02-01-2006, 12:56 AM
We did have a cd deck recently. I removed it and checked the wiring job. They did use the Honda jumper to connect the deck directly to the stock harness without any cutting. So I believe the issue is not there. Plus the deck was installed 2 weeks before any of this popped up. There is no indication of a bad ground in the doors, although I will make a full check of them tomorrow.

Okay, this is the current situation. I replaced the alternator with a high quality rebuild. The car is running fine and the MIL/CEL is not lit. No other indicator lights are coming on, which should indicate no ICU failure (my wiring diagram refers to these as multiplex units).

I replaced the blown rear power window fuses (20A). Turning the key to II blows them instantly. I then removed one of the rear door panels and accessed the power window motor and switch wiring. With the key at II and the switch connected, there was no motor response. With the switch disconnected, I was able to confirm 12V at one terminal of the switch connector. I then jumped the 12V directly to both terminals of the power window motor and there was no response.

I need to know the nature of the power window circuit. With the 20A fuse blown, I am assuming that the power window motor is still grounded. If this is the case, and I have no response from the motor, can I safely assume the motor is blown. If the motor is blown, is there any way it will blow the fuse when the key goes to II. Anyone heard of a blown window motor blowing the fuse when the key goes to II? Any info is appreciated.

superbluecivicsi
02-02-2006, 01:21 AM
a helms with its very detailed wiring diagrams would be a helpful map right about now ;)

asilomar244
02-02-2006, 02:07 AM
Helm's manual has been ordered and is supposed to arrive tomorrow. I removed the window motor. Jumping battery voltage to it gives no response. Resistance is 1.5ohm. I think it is completely blown and shorting the circuit to ground. Ordering window motors tomorrow. Let me know what you think.

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