Fourstar787

Fuse 25 under dash had blown resetting clock amongst other things. I replaced it all good for a while. It's blown again. Are there any common culprits?

engifineer

25 is the ECM, gauge assembly, . 22 is the audio unit which would be the clock .. are you sure it was not 22?

Fourstar787

sorry I should have stipulated year. It's an 07 AP1. Which includes dash clock. Yes deffo 25.

engifineer

ah ok. Can you isolate when the fuse is blowing? Aka, after you turn on key, turn on lights, etc? Operate the items listed on that fuse circuit one by one and see if it does it after one of those. Or, does it pop as soon as you put a new fuse in and turn on the key?

Sorry I was going by a fuse diagram I had on my PC from an AP1 I have the full shop manual for both models ... in my shop ... and there is a raging thunderstorm going on so did not go down there to grab it yet

Fourstar787

it worked fir a couple days. My partner used car today and said clock had reset again and heater control memory has gone again.

Fourstar787

okay as I plugged in a new fuse I hear a chirp like an alarm arming then it blows...... no ignition even on.

engifineer

Hmmm have an aftermarket alarm? I think Honda may have offered an alarm option for the AP2 but I am not sure on that. If there is one and you can unplug its harness easily, you can first see if the issue goes away with it unplugged.

You have now isolated the issue to things that do not require ignition power though. Troubleshooting is all about isolating and ruling things out as you go.

If it were mine, I would first disconnect the battery, pull the fuse and check continuity with a meter from the output side of the fuse to ground. You can determine which side is the load side by checking with a voltmeter with the battery connected. With the fuse out one side will have voltage on it, the other is the load/output side of the fuse. This will tell you if there is a short in an unpowered situation. If there is, then I try to isolate various portions of the circuit if I can. So, unplug harness to radio, see if short is still there. Unplug harness from gauges, see if short is still there, etc. Granted, some of his will be harder without the electrical diagram to go by. You likely will read some resistance to ground with the power off but it should be pretty high. A short blowing the fuse is going to be lower than 1ohm for example, and you should be seeing much more resistance than that.

If you do not have access to a meter or are not comfortable poking around with that stuff, then of course get someone to help with it.

If there is not a short with no power to the car, then I focus on the items powered by the circuit (Aka they may be drawing too much current when powered).

You could try just disconnecting something, putting in a new fuse, etc but you are just going through a lot of fuses that way and may still not find the actual root cause. So a meter is what you want at this point.

Has anything recently been changed? New head unit, alarm, anything at all been done that would affect the wiring? Signs of mice anywhere in the car from the winter?

Fourstar787

I'm clearly on the right lines as my train of thought is same as yours. I do have a service manual with diagrams for each circuit. I'm happy enough using a meter.

The car is new to us. Inherited. seems 99% original if im honest. But im unsure how long the problem has existed as its sat for 12 years unused.

No aftermarket alarm just whatever the UK version for the year 07 came with.
As for mice..... there were some droppings in the airbox but I can't currently see any chewed cables.

I do also have vsa and activation light permanently on. No imobilizer light showing on dash during test. (Could be explained by fuse 25 being blown)

thanks for your responses thus far. Im awaiting a cable to arrive to use hds and see if there are any DTC stored.