dth0ng69

Just got a 99 EX Coupe. In trying to get it registered, i had to pass emissions. No check engine light, went to take the emissions test and they said OBD2 Monitors not ready, and told me to drive around.
I drove around for 50 miles and came back still same result the monitors are not ready (Cat, Evap, O2) drove 50 more miles came back to the same results.

Did some research and ended up checking my 7.5 (Back up) Fuse under the hood and sure enough it was blown.
After doing some research I am going to take out the Aftermarket Stereo to check for a loose/grounded out blue/white wire?

Heres my dilemma, What are the symptoms when the 7.5 (back up fuse) (under the hood) is blown? Because the aftermarket deck turns worked perfectly fine with the back up fuse blown. I am scared the guy did a hack job behind the stereo and swapped ignition wires around and stuff.

What should I look for in the reason why that fuse is blown?
any help suggestions or feedback would be greatly appreciated.
thanks for reading !.

Former User

The Back Up fuse protects circuits for the ECU, radio stations, heater control panel settings, and clock time memory. For a car with stock wiring, all those functions would be lost if the fuse is blown.

dth0ng69

hey RonJ so your saying that Stereo shouldn't of worked? and my heater control panel settings wouldn't work? if that fuse was blown?

thanks for the fast reply..

Former User

If the wiring is still like stock, the stereo would not work or would not remember radio stations, the clock would not remember the correct time, and heater control panel would not remember whether the A/C was on or off after the key is tuned off.

dth0ng69

RonJ you are right as always, i take out my Headunit and i see a Hack Job...
Here are some pics.

Here is the Wiring of the Deck. pretty bad wires are crimped up.



Now I know why my stereo was able to turn on after blowing my 7.5 back fuse in the hood.
The 12v Battery wire could not be located (typically whitew/yellow stripes?) so I follow the battery wire that goes towards the underdash fusebox.




And it is connected to the the top left corner of the relay/fuse box underneath the dash. Right above fuse #25 under the dash.




My question now... is the 12v battery wire connected to the fuse box horrible?
I cannot located the stock white w/ yellow strip 12v wire..

thankss

Former User

The constant power wire from the 7.5A hood Back Up fuse (#47) is a Wht/Blu wire. Try to locate it to see whether it is exposed and shorting out. The same Wht/Blu wire runs to the clock and to the rear of the heater control panel.

dth0ng69

ok i re wired the white/blue wire and now im just hoping for the best.

Former User

Good luck.

Agaona03

Anyone know why there wouldnt be any power going to fuse #31 under dash on a 98 honda civic lx 1.6.?

Wared King

muellersfan

TomCat39

Yeah, but for once a helpful addition for future searchers.

Patton_

For those who still want to know why OBD2 Monitors Not Ready in this case - the ECU still works without the backup fuse but at each moment you switch off the engine the memory of the ECU is lost. Every new start is (literally) like you just reseted the ECU memory. Had same problem with my 99 LX Sedan A/T. Previous owner did some workaround with the original stereo wiring and the fuse blew constantly. In my case the CEL was turning ON randomly and I was not able to recovery the error codes from the ECU.

tony_2018

What a bummer, thats why you don't cheap out on harnesses if you don't want to deal with electrical headaches.