96 Cobra Electircal Issue
 

Alright, my first post is going here because I don't think this is SVT specific, and I haven't been able to find anything related to this anyplace else.


First of all, the car did sit for a while. It seems to have power, but will under no circumstance attempt to turn over. My initial thought was the battery, so I replaced it. Still no go. I'm not getting any theft light at all, so I don't think it's the PATS.


Here's where it gets really messed up. The radio got stolen a while back, and my dash is now a mess. My dash clock is dead, dome light dead, and unlock button causes my running lights to turn on while held down, failing to lock or unlock the door. No door chimes. I consistently blow I/P fuse #8 (radio, courtesy lamps, power mirror, remote keyless entry, clock). I assume it's a bad ground, but in the wiring mess I'm having a hard time isolating the grounds.


A/C controls all work, wipers, flashers, rear defrost, dash lights, headlights, power windows... ALL WORK.


I'm hoping somebody here can tell me where to check for the ground points behind the radio so that I can sort of work it backwards, and see if I can reground everything. Also, I'd like to know if there's anything computer controlled on this circuit that would specifically stop the car from trying to start at all, or does the radio itself have something to do with that?


I'm super sorry if this has been covered elsewhere, but any input would be appreciated. This kind of came up suddenly, I had previously started and ran the car twice a month without any issues.

Sorry, I meant to post this in tech. Please move if you get the chance, mods.

Hi Crappy Cobra,

Firstly I apologize in advance if my instructions/explanations sounds elementary or over explanatory..
Secondly, keeping this in mind, fuses mainly blow from a fault on the (+) positive voltage side (power-side).. It's normally a short or there is too much amperage being demanded.. That being said I'm not thinking it's a ground issue, per say..

Next, I believe you're blowing fuses because you have an exposed wire touching bare metal, another exposed wire, component or a frame/grounded chassis piece somewhere in that bundle of wires the thief left you after doing a hatchet job to retrieve your radio. He wasn't actually trying to do a quality uninstall, just steal and quickly leave..

What we don't know is if the thief actually tried to steal the car first before taking the radio.. Which may have triggered/defaulted/damaged your Anti-Theft measures..

Even with an IP Fuse 8 Blown, it should still rotate the engine/crank.. This also appears to be a Batt Fuse that has +12V Continuously but shouldn't affect Engine/PCM function or Engine Rotation..

To my knowledge the PATS system simply shuts the engine off when the coded key isn't inserted or within a certain proximity to the receiver.. If you have an extra/aftermarket alarm system also installed then that could be the source of your non engine rotation via a starter kill or wire being cut at the time of radio theft but for know we'll just work around that..

Stating that your car was cranking before the radio theft and assuming all other original unaltered wiring exists, the problem should be found in that area of dismantled wiring.. So let's try this first..

Start by getting a full assortment of fuses, plus extra 10A fuses, good flash light, multi-meter or light tester and electrical tape..
1. Disconnect the battery ground cable connection..
2. Take the electrical tape and cover the end of every lose wire you can find behind the console area where the radio was..
3. Look around again with your flashlight.. You want to cover and isolate every exposed wire to keep from blowing fuses and doing any more electrical damage..
4. Next replace all the IP fuses, or check/clean the contact ends to reinstall.. This lets you know that you'll have good current flow throughout..
5. With the damaged wires capped and all the fuses loaded, reconnect the battery, turn the key and see if any fuses blew.. If any did recheck for stray uncapped wires or loose connections..
6. While turning the key pay particular note to whether or not your "theft" light and all other dash lights did the initial bulb check..
7. If that's all good then try to start your car.. Hopefully it starts..
8. If not, With the ignition on, check all your fuses again (Hi and Lo Current)..
9. If that's all good and you're still not starting then we can go further because there are some questions I'll need answered to tell you where to go from there..

EXTRA KNOWLEDGE
The 1996 Mustang Owners Manual states that Fuse location 8 (10 Amp) controls:
1. Chimes for Key in Ignition
2. Courtesy Lights
3. Engine Compartment Lamp
4. Glove Compartment Lamp
5. Power Mirrors
6. Radio (MCM)
7. Instrument Cluster (MCM)
8. Clock
9. Trunk Lamp
10. Anti-Theft (Door Open Signal)


After researching further I've found that there are also some additional IP fuse locations that interface with the Anti-Theft system..
1. Fuse Location 6 (15 Amps): Anti-Theft Module (shut-Off)
2. Fuse Location 16 (20 Amps): Anti-Theft Module

Also found in 1996 Mustang Owners Manual, in the Engine Compartment High Current Fuse Location [Top Three Fuses Middle Row] labeled as IGN SW, there are three 40 Amp fuses, check them as one feeds the Anti-Theft Module (shut-off) and another controls the starter relay.. Additionally check the 50 Amp fuse [Fourth Fuse Down Middle Row] labeled as HD LPS, there should only be one fuse of that amperage rating..

**The factory keyless entry also uses the radio antenna for signal reception so without the radio connection and/or completed correct wiring it could be a reception problem**