92 Accord LX w/H22A : Fuse 28 (10A ECU) pops with main relay plugged in
04-13-2012, 12:39 AM
#1
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92 Accord LX w/H22A : Fuse 28 (10A ECU) pops with main relay plugged in
The swap has been running fine in the year I've had it in and seemingly out of nowhere the 10A ECU fuse is blowing.
When the problem first arose, the main relay was unplugged and plugged back in, then I was able to get home on a new fuse. The relay's one of those things known to go bad (I did re-solder the whole board, for the record, and it seemed to test well), so that along with the fuel pump and battery ground were 'reset' by a simple unplug-replug. The fuse popped again the next night, so the relay by itself was 'reset' a couple more times only to blow more fuses when turning on the ignition with it plugged in. So it must be something in the main relay circuit, correct? The car and my Hanes/Chilton books are sitting at a friend's house, so I'm going off memory here, but are we correct in narrowing the problem down to the 02 sensor, IACV (that's the thing on the front of the plenum, correct?), and injector resistor box circuits, since those are the only ones connected to that particular fuse? Do diodes fail in such a way that electricity can pass through them the 'wrong way,' and therefore open the possibilities up to anything in that relay circuit? The resistor box was actually another thing we replaced and the car ran fine for a couple days. I had been running the Prelude box that came with my engine from HMO, but I still had the F22A1's laying around so we swapped that one in. I opened up the ECU (P13 for an automatic... my car being auto) and everything 'looked' okay - no fried-looking resistors or leaking capacitors, anyway (I had to solder in some new parts in my old TCU when that was giving me schtick, so I kinda know what to look out for).
I still felt nervous and have been taking the long route anywhere I go just to drive the car as much as possible to see if it would die again. Did well on a long drive last night. Then again to and from the parts store and work, though I did feel two or three hiccups during acceleration in all this driving. But lo and behold, I ended up coasting into a parking lot tonight.
Any help from the experienced techs on here, especially with advise on what to test and what DMM values to look for, would be greatly appreciated. This kind of diagnosis is mentally exhausting.
When the problem first arose, the main relay was unplugged and plugged back in, then I was able to get home on a new fuse. The relay's one of those things known to go bad (I did re-solder the whole board, for the record, and it seemed to test well), so that along with the fuel pump and battery ground were 'reset' by a simple unplug-replug. The fuse popped again the next night, so the relay by itself was 'reset' a couple more times only to blow more fuses when turning on the ignition with it plugged in. So it must be something in the main relay circuit, correct? The car and my Hanes/Chilton books are sitting at a friend's house, so I'm going off memory here, but are we correct in narrowing the problem down to the 02 sensor, IACV (that's the thing on the front of the plenum, correct?), and injector resistor box circuits, since those are the only ones connected to that particular fuse? Do diodes fail in such a way that electricity can pass through them the 'wrong way,' and therefore open the possibilities up to anything in that relay circuit? The resistor box was actually another thing we replaced and the car ran fine for a couple days. I had been running the Prelude box that came with my engine from HMO, but I still had the F22A1's laying around so we swapped that one in. I opened up the ECU (P13 for an automatic... my car being auto) and everything 'looked' okay - no fried-looking resistors or leaking capacitors, anyway (I had to solder in some new parts in my old TCU when that was giving me schtick, so I kinda know what to look out for).
I still felt nervous and have been taking the long route anywhere I go just to drive the car as much as possible to see if it would die again. Did well on a long drive last night. Then again to and from the parts store and work, though I did feel two or three hiccups during acceleration in all this driving. But lo and behold, I ended up coasting into a parking lot tonight.
Any help from the experienced techs on here, especially with advise on what to test and what DMM values to look for, would be greatly appreciated. This kind of diagnosis is mentally exhausting.
04-13-2012, 01:15 AM
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Re: 92 Accord LX w/H22A : Fuse 28 (10A ECU) pops with main relay plugged in
Check the wiers going to the O2 sensor that fuse should controls the heater ckt. A shorted inj. mabey or a short in inj. wireing I would disconect the O2 and retest go from thair Want a good tip? Use a test lite or a ckt. breaker for the fuse that way you do not burn up 20 fusesTry this and repost
04-13-2012, 03:48 PM
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Re: 92 Accord LX w/H22A : Fuse 28 (10A ECU) pops with main relay plugged in
The 02 wiring looks to be in great shape. Injectors tested fine, they were all 2.4-2.5 ohms. Tested the injector resistor box and it too was all within spec. The IACV itself tested good, but at the connector there was battery voltage coming from the YLW/BLK wire and 10-point-something at the BLK/BLU. A voltage drop across the connector showed 1-point-something volts (should be battery voltage?). That BLK/BLU wire runs straight from the valve to the ECU - is there any way to test whether this circuit is shorting out in the ECU itself? That's a pricey box to buy just for testing purposes.
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