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naturboy · Jan 25, 2009, 12:46 PM

I have checked the main relay. All is well. Grounds are good for the ECU. Power is good for the ecu. The CEL does not go out, fuel pump does not get +12v(#8 of main relay not pulling down from +12V), CEL on when jumper put in-no flash codes, +5V reference is on at sensors, +12V is on at injectors, no injector earth signal, ecu fuses good, main relay clicks 1st click when key is turned.
:confused::confused::confused:
What would cause the #* of the main relay to not pull down?

I am down to blown ECU but there is no apparent damage on the PCB.

TxGreaseMonkey · Jan 25, 2009, 01:10 PM

The problem is with the ACG (ALT) (S) fuse, in the underdash fuse box; ECM (perform the K-Test, below); Main Relay; or the Ignition Switch. Perform tests in that order.

The K-Test: Remove the MAP Sensor connector and turn the ignition switch to ON (not start). Using a multimeter, check for 5 volts going between the MAP Sensor connector's reference wire (+) and ground. As you look at the connector, this is the socket on the right. Really press the black test lead into a cleaned main ECM ground on the thermostat housing. If the voltage is low, it's probably indicating ECM failure. Most failed ECMs will record a fraction of a volt. To me, the K-Test is simple, elegant, and accurate.

Be sure to clean the main ECM ground on the thermostat housing. My bet is that the ECM has failed or the main ECM ground has corrosion. Terminal #8 is the ECM grounding terminal.

naturboy · Jan 26, 2009, 07:43 AM

Thank you txgreasemonkey,

Originally Posted by txgreasemonkey

The problem is with the ACG (ALT) (S) fuse, in the underdash fuse box; ECM (perform the K-Test, below); Main Relay; or the Ignition Switch. Perform tests in that order.

The K-Test: Remove the MAP Sensor connector and turn the ignition switch to ON (not start). Using a multimeter, check for 5 volts going between the MAP Sensor connector's reference wire (+) and ground. As you look at the connector, this is the socket on the right. Really press the black test lead into a cleaned main ECM ground on the thermostat housing. If the voltage is low, it’s probably indicating ECM failure. Most failed ECMs will record a fraction of a volt. To me, the K-Test is simple, elegant, and accurate.

Be sure to clean the main ECM ground on the thermostat housing. My bet is that the ECM has failed or the main ECM ground has corrosion. Terminal #8 is the ECM grounding terminal.

The ECU fuse under dash is good and powered with 12v+, the main relay is working properly, the MAP sensor plug has 3 wires and the outside ones have +5v and +4.76V, the ground is loc drivers side of the engine on the side of the intake plenum and is good, how do I test the ignition switch?

Thank you,

TxGreaseMonkey · Jan 26, 2009, 07:52 AM

Here's how:

https://www.askmehelpdesk.com/cars-t...tml#post224652

Check for wear, pitting, or melting. Easy job. Did you check all underdash fuses with a test light or multimeter, including the Starter Signal Fuse?

Since the ECM and the main ECM ground are fine, the ignition switch is the problem. The ignition switch and the ECM control the second relay inside the main relay, which wasn't working. Since we know the ECM is fine, replacing the ignition switch will allow the second relay to click and solve all of your problems, provided all fuses are good.

naturboy · Jan 28, 2009, 11:32 AM

I checked all of the fuses with a high end fluke multimeter. They are all good. The K test Passes every time. The Ignition switch passes every time. Is it not possible that the ECU is partially fried? It is just not pulling the #8 of the main relay down to zero V. The ignition switch is doing what it is supposed to as well as the main relay. Do you know where to get a pin out for a 95 Accord? I tried Honda Hookup but never received the activation email. It started intermittantly working two days ago and worked for a bit but yesterday it was out again. Thank you txgreasemonkey!

TxGreaseMonkey · Jan 28, 2009, 12:40 PM

Again, we are down to the ECM or the ignition switch. It may be that your ECM is intermittently failing--CEL stays on at times and sometimes goes out. These cars will not start, if the CEL is on. If you perform the K-Test, when the CEL stays on, if likely will indicate the ECM is bad. Because of the age of your Accord, the ECM needs replacing anyway. I recommend replacing them on this generation of Honda every 120,000 miles or 10 years, whichever comes first.