A week ago I purchased a 1992 Honda Accord with 206K miles. It has been running fine until this morning. Battery is good but it won't start and nothing electrical comes on. Did some on-line research and issues point to the ECM / ECU. I did an ECM reset and now when I turn the ign key on, the dash lights up, then when I turn the key to "Start" there is a click and everything goes dead again. First question is - where is the ECM? Second question is - can I test the ECM with a volt meter? Third question is - where is the best (and cheapest) place to buy an ECM, it that is the problem? Thanks - Mike

Here's what I would do:

. Remove and fully charge, or replace, the battery. Most auto parts stores will do this for free. Be sure the clean the battery terminals and cable connections, including to the starter motor. Examine the cables for hidden corrosion and breaks.

. Test all under hood and under dash fuses with a test light or multimeter.

. Check the ignition switch for wear, pitting, or melting.

. Verify that the Check Engine Light (CEL) comes on for 2 seconds and then goes out, when the ignition switch is turned to ON (Position II). Only if the CEL stays on should you suspect the ECM is bad.

Engine Control Module (ECM) Replacement

1. Disconnect negative battery cable, after recording radio codes.

2. Remove right door sill molding, pull carpet back, and expose ECM.

3. Remove three 10mm bolts and one 10mm nut securing ECM cover.

4. Separate ECM cover from harness carefully.

5. Press connector release, going to connectors A, B, and D, and carefully pry connectors from ECM, using a small screwdriver.

6. Spray connectors with WD-40, plug connectors into new ECM, and button things up.

I suspect the battery is bad.

Quote:

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Originally Posted by TxGreaseMonkey

Here's what I would do:

. Remove and fully charge, or replace, the battery. Most auto parts stores will do this for free. Be sure the clean the battery terminals and cable connections, including to the starter motor. Examine the cables for hidden corrosion and breaks.

. Test all under hood and under dash fuses with a test light or multimeter.

. Check the ignition switch for wear, pitting, or melting.

. Verify that the Check Engine Light (CEL) comes on for 2 seconds and then goes out, when the ignition switch is turned to ON (Position II). Only if the CEL stays on should you suspect the ECM is bad.

Engine Control Module (ECM) Replacement

1. Disconnect negative battery cable, after recording radio codes.

2. Remove right door sill molding, pull carpet back, and expose ECM.

3. Remove three 10mm bolts and one 10mm nut securing ECM cover.

4. Separate ECM cover from harness carefully.

5. Press connector release, going to connectors A, B, and D, and carefully pry connectors from ECM, using a small screwdriver.

6. Spray connectors with WD-40, plug connectors into new ECM, and button things up.

I suspect the battery is bad.

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When I turn the key to "ON", no dash lights, no horn, radio, nothing. If I disconnect the battery (it tested good) and wait a few minutes, then reconnect the battery, then turn the key to ON, the dash lights up, radio works, etc. Then when I turn the key to "Start", I hear a click, then everything goes dark again. I can trace 12.8 volts all the way to the fuse panel and past the 80 Amp fuse link. The Chilton'e wire diagram (I am a retired ET) shows the ignition switch feeds the ECM which then goes to the starting system and several other areas. Unless there is a in-line fuse link after the fuse box, that is blown, I'm thinking it's the ECM / ECU. The wireing diagram doesn't show any in-line fuse link (like some cars have); just the fuse links in the fuse panel under the hood. What do you think??

Now, I suspect the ignition switch is bad. It's something basic and simple, not mysterious like the ECM.

When you turn the key to "ON" the instrument panel lights come on. When you turn the key to "Start" there is an audible "click" (starter relay I presume), and then everything goes dark - meaning the instrument panel, lights, horn - everything. If I disconnect the battery for a little while and reconnect it, the electrical system is functional again, until you turn the key to "Start". If I disconnect the starter solenoid, and re-set the ECM, the instrument panel does NOT go dark when I hit the starter. Any ideas? I'm 10 miles out in the woods and it will cost $65 to tow into town, so I really need to find the problem myself. I have a Chilton's manual and it shows an "ECM Main Relay" between the ignition switch and the ECM. Maybe this relay is the problem? I can't find a locator chart in either the owner's manual or the Chilton's manual.

The best clue appears to be the electrical system goes completely dark when you hit the starter. The electrical system only comes back on if I disconnect the battery for a period (30 min?). Then the ignition switch works, dash lights come on, CEL, etc. - UNTIL I turn the key to "Start". Then it goes "click", then dead.

Sounds like a bad battery. Can you jump start the car from another vehicle?

Did you replace the ignition switch?