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My Accord Won't Start, Keeps blowing ECU fuse. Help!

My 1991 Accord was running fine, (never winter driven), ECU fuse blew, changed it, now it blows as soon as the key is turned. I tried changing the fuel pump, distributor, but same prob. The computer under the passenger carpet is dry, and looks like new. No water damage. I also installed my fuel pump relay in a friends similar Accord, his started rite up!

Here’s a vid on youtube I made. HELP!!!



http://www…F_x_IKV1lI

The fuse is an indicator of something wrong . . . why did it “blow” in the first place? I would check all connections from the ECU fuse outward . . . ground? Bad connectors? Could take a while, but there has to be a reason it blew in the first place. Maybe you could swap another ECU for yours (salvage yard). Electrical problems can take a wile. Good luck! Rocketman

I just watched your video and add this comment. It looks like either a plug wire or coil wire is missing on your distributor cap. Also . . . it appears that you are replacing the blown fuse with a fuse of another color, can’t see the size of either. Did you try the right size fuse? Using the wrong (too “weak”) fuse will certainly blow if a higher one is called for. Rocketman

Are you using any kind of a trouble shooting guide or repair manual? Seems fairly straight forward to me. If you are blowing fuses, that means an over-loaded circuit and if they blow immediately a dead short. The short can either be in the wiring with two wires shorted together or more than likely just a fried computer. I think you need a new computer (ECM). So when you get blown fuses its either a fried component connected to the circuit or the wiring itself. Don’t know why you would be looking at fuel pump or distributor.

To see if the short is due to a bad ECU simply remove the connections to it and see if the fuse then blows or use a ohmmeter to check the resistance on the load side of the fuse. The fuse most likely supplies power to other devices, possibly some engine controls, and the trouble is really there. I don’t have any service data that covers your car. I suggest you go to your library or purchase some service data for your car so you will have a drawing to show you where to look for the trouble. You can download data from alldata.com for a reasonable price.

The ECM fuse is #28 on the wiring diagrams. It’s a red 10 Amp fuse. When the ignition switch is turned on, power from the ECM relay makes contact (inside the ECM Main Relay [also, called the PGM-FI Relay]) to the circuits it powers.
The yellow/black wire from “the relay” branches. One branch goes to the idle air control valve, turns black/blue and goes to terminal A9 on the ECM. The other yellow/black branch goes to the O2 sensor, fuel injector resistors, fuel injectors, and to terminals B1, and A25 on the ECM.
The other direction from “the relay” contact, goes to the pull-in coil of the other relay (this is a dual relay), and on a green/black wire, goes to terminals A7, and A8 on the ECM.
Go to www.autozone.com and register your car. You can,then, see wiring diagram Fig. 37, which has the information the above words came from. http://www.autozone.com/autozone/repairinfo/repairguide/repairGuideContent.jsp?chapterTitle=Wiring+Diagrams&partName=Chassis+Electrical&pageId=0900c1528005f9fc&partId=0900c1528005f8f0
Disconnect the ECM (Engine Control Module). Turn the ignition switch on. If the ECM fuse still blows, the short is somewhere beween “the relay” and the ECM.

From your video, “Smoke On Da (Fuse)…Water…”, the electrical short fixed itself. When it comes back (blows the ECU fuse), check the O2 sensor wire, first. The wire covering may have burn through on the hot exhaust manifold.

Wow, good answer… You’ve taken some of your valuable time. I appreciate it. I’ll try disconnectiong the computer, and crank it. I did this a month ago, but forget the result… Hate to spend $50 for a computer, just to plug it in for a minute, quick crank…

Well, hellokit wins the prize!

I read his response, thought about the Oxy sensor, jacked up the car, and the wire was wrapped around the axle! I plugged stuff back in, as only the wiring harness plastic plug was missing, and she fired rite up!

Now the "check engine " lamp is on, even after removing the battery cable, but she seems fine!

Here’s a vid of my escapeades!

I saw your latest video. Saturday Night Live (SNL) may be calling you…or, maybe, not.
A safety note: you jacked the car up rather high, and put jack stands under it. So good, so far; but, as an extra precaution, I like to leave the floor jack in place, under the car, with some tension on it. I don’t want to bench press a 3,000 pound car. That’s a little above my weight limit.
I saw that the oxygen sensor wires had splices. I don’t like splices because they can lead to error signals and other problems you can live without. To me, a few more dollars for an oxygen sensor with a complete pig tail, with connector, is worth it.

I installed the generic sensor 7 years ago, and occasionaly the check lite comes on, not very often. Actually, I used a log to get the car higher with the floor jack, and it rolled off, and did a bit of damage. A couple of neighbors saw what happened, but I was fine. I’d take your advice, but we’ll be trading up to a Pilot soon, we hope. 2006 with the 6-3 cyl engine. We’ll see what we can find. Hope to buy it in Florida to avoid the rust belt, and grease spray it to inhibit rust from the SALT!!!