Hi. I have a 94 civic dx that will not start. It died driving down the road and had to be towed. I have no spark and no fuel. CEL comes on and stays on as long as the key is on. I have no main relays clicks. I have applied battery voltage and ground to the various pins of the relayas indicated in the repair manual and it tests ok (good strong clicks). I have checked for voltage at the connecter for the main relay (forget the pin/connector number) and I do not seem to getting current to the main relay. So far I've checked fuses, replaced ECM and ignition switch from a wrecked salvage vehicle. Anyone have any other ideas?
Thanks.

 

Possible MAP sensor circuit problem?

Pull the CEL code(s) as detailed at the link in my signature. Post the retrieved CEL codes in this thread for more feedback.

Edit: Did the timing belt snap?

 

You need to see why power is not reaching the main relay and possibly some of the power inputs to the ECU. Check that power is reaching the ignition coil primary terminals with the key on; that should happen regardless of the condition of the main relay and ECU (It will not spark, but you should have constant battery voltage). Did you check the main fuses under the hood?

Edit: And of course losing a ground is the same as losing power. Everything ECU-related grounds back to the wires on the thermostat housing. Measure voltage on the various "ground" wires and make sure they really are close to zero relative to battery minus.

 

Unable to retrieve codes. The BKUP fuse under the hood which as I understand is the ECM memorywas blown. When replaced, all parking lights come on (key off, light switch off). Not sure if this condition existed before this failure. Assuming this is the reason for no codes when jumping the test connector. Tried replacing the fuse after alternate ECM was installed with same results.
I've removed and cleaned the ground connection at the thermostat housing but have not checked for any voltage. I can try that.
Haven't checked the timing belt but it sounds and "feels"normal when cranking (I've cranked engines with broken timing belts before and it's weird with the goofy or no compression).I should still get power to the main relay and fuelI would think. I guess it would be easy enough to make sure so I will double check.
Thanks.

 

MK378, I'll follow your suggestions as well.
Thanks.

 

You have a short circuit somewhere between the service connector and BACKUP fuse and ECU. This is the reason that the CEL stays ON. You cannot know whether you have a sensor fault until the short is fixed. I don't think this would cause a no-start problem, though.

 

About the only place the BACKUP circuit and the parking lights get close together is the radio. If it's an aftermarket radio you may have some shorts or miswiring behind the radio.

 

You should consider that the short in the Service Connector and parking lights circuit is related to the lack of power to the main relay. I think that if you locate the Service Connector/parking light short circuit or the damaged wire between the battery, ignition switch, and main relay, then you are likely to find the source of all the problems.

Edit: What is the outcome of the tests in the diagram?