Checked Grounds, electronics still jacked?

[1990StangGT]

On my 99 Gt I have been having tons of problems, I was running alot of power out of my cigarette lighter when all of the sudden the sound of the radio goes off, radio still on but mach 460 amps off, no blower motor for a/c, no instrument panel lights,no door locks, No ODB port power up for my sct x cal but it powers up fine in my f-150, before all this a few weeks ago my blinkers and windshiled wipers did not work all of the sudden either. I have checked in my clymer manual and have linked down a ground that leads all these but a couple together but its fine. So my question is since all fuses are fine as well as the ground I checked which was supposed to be in the back luggage compartment what could be casuing this? Am I looking at the diagram wrong or is there possily a better diagram someone has for all these? I just want my darn diagnositcs port to power up so I can tune my car. Thanks and any help would be nice I am stumped.

 

[1990StangGT]

Oh and check engine light will come on but I can not check it, car is running rough idles little rough then fine until 2k then starts sputtering like crazy, same at WOT too. I want my sct so I can put on a different tune see if that helped this was after I got some water in the engine while cleaning and even put in new plugs but problems have carried on any imput on this would help too thanks.

 

[1990StangGT]

anyone?

 

[Nater]

If the car grounds and fuses look fine, I would turn to the engine side. Check the battery and alternator to see if they good. If they are, check the engine ground. I don't think it would be water in the fuel/engine as that is confined to one area. It would not cause the electrical in the car to go crazy.
Go over the wiring under the hood pretty carefully to see if a power wire is grounding on the chassis; a bolt is loose for a power or ground wire; the alternator is bad; battery is bad or battery terminals are loose.

 

[1990StangGT]

Battery and alternator are fine, like I said the problems where before I cleaned my engine bay and car is running better but still sputters at wot. But I am just wanting my port to power up I could care less about anything else really but would like these fixed as well. The blower motor would be nice as well, like I said too much voltage was taken from the cigarette lighter and everything stopped working I only checked the ground in the luggage compartment but the ground looked great so is there any other grounds I could check or any other advice? Maybe a better wiring diagram than I have currently? I had someone tell me there is a ground that runs some of these componets but not all and it is located in the center firewall? Will I have to pull my dash off to reach this ground just to check it? This is a pita lol.

 

[Torinalth]

few things. there is a ground for the 460 (as well as a few others) behind the radio on the right hand side. its just a black screw with i believe 3-4 lines running to it. check into that.

after that is done lets go backj into the engine bay... there are three main points for the power line that need to be looked into... the battery to the chasis ground, battery to alternator, and alternator to chasis. just follow the power lines and see where they lead. make sure they are all secure and check for bare wire/fraying and lightly bend the wires see if it bends really easy in case of corosion has eaten the line at some point.

i am not familier with anything in the trunk area for a grounding spot... however when i removed my rear seats i kinda remember there being a grounding there... i MAY be mistaken so take this with a grain of salt, but pull the back seats up and see if anything looks out of place. also, if you have a voltmeter do yourself a favor and recheck all the fuses using continuity to see if its not broken and just isnt visual.

remember, there are 2 fuse boxes, one inside and one in the engine bay. check both. and if i am not mistaken i thought there was a fuse located for the computer either on or near the computer. might want to look into this as well.

Torinalth

 

[1990StangGT]

Ok all wires in engine bay are fine, I have used a test light on every single fuse, pulled the seats everything is fine there, as far as the fuse on or near the computer I need more info on this please. I am soooo stumped on this never had so much trouble. And if this fuse for the computer is blown would'nt casue more problems than just what I have like not starting at all. Oh by the way I have no dome lights either thanks and you guys are at least helping keep the suggestions and info coming I really do not want to get raped by taking it to a shop.

 

[Nater]

Is there power to the fuses? If yes, there must be something wrong in a harness or wire loom someplace. Are the issues on one circuit or many?
It could be that a wire has had its coating rubbed off and is grounding out.

 

[1990StangGT]

Ok looking at my haynes wiring diagram in the back of book it says the cd player, radio, a/c illumination, intrument cluster, are all on same circuit, each all having thier own ground, does not say if any others run off same circuit they do not provide a complete diagram just some b/s that does not do much for explanation I need a better diagram. Yes power to fuses, the coating could of rubbed off but not likley considering this happened right when I was pulling alot of power from my cigarette lighter, the wierd thing is the defrost works but air will not come out of vents only defrost. Anyone have a diagram link?????

 

[Jinx]

...this happened right when I was pulling alot of power from my cigarette lighter...

Just curious. What did you have plugged in, pulling that much power? I've seen spotlights do that (usually just blew a fuse though).

Is it possible that you burned out a relay in the outer fuse block?

 

[1990StangGT]

I actully had a plug in space heater, I bypassed my heater core becasue they keep going bad still can not figure this problem out but yea after 20 mins of this running all of the sudden bloop all these problems. And I was told a relay will not run these componets? I will try it but need to know the location of the relay?

 

[1990StangGT]

Still have no figured out this problem and called around to dozens of shops,posted on numerous forums WTF!!!!!!! Can anyone help me on this issue anyone please?

 

[ultrashock2112]

I really don't think it would be a ground problem. Since the whole car's chassis is ground most electronics have their own grounds directly to the chassis. The problem is most likely the 12V not getting to the devices - if you say you don't have any blown fuses, then you don't have any shorts. Are all your fuses the proper rating? Do you have a fuse in there that is higher than spec? I'm honestly suprised that you were able to run a heater off the cigarette lighter, they draw a lot of current. If you have a fuse with higher amp rating than spec you could cause major problems. e.g. wires can melt etc.

Another thing to think about... Do you have an aftermarket alarm installed? Do you know who installed it? It is really easy to f**k up installing one and a lot of installers don't know what they are doing.

... Maybe a defective GEM? Don't know much about testing them though.

 

[n0v8or]

I have the '01 wiring diagrams . . . not sure how close they are to a '99. Do you have a voltmeter? You can probably buy a cheap one for less than $10 at Wal-Mart. Voltmeters are a lot more useful than a test light for tracking down electrical problems. A voltmeter will more easily detect a low voltage caused by damage to a wire (or a corroded connection), where a test light may just light a little less brightly, and you won't notice.

Usually, there are 2-3 levels of circuit protection. The first is the fuses mounted under the dash. These may be backed up by another fuse under the hood. Finally, there is usually a "fusible link" between the battery and underhood fuse panel. The fusible link is a protection of last resort. It is special wire that is designed to burn out without starting a fire. In theory, it burns out and interrupts the power before the harness wires can overheat or be permanently damaged by an overload.

Assuming 12V is not reaching the circuits you listed, it should take no more than 15 minutes to isolate the problem with a voltmeter.

 

[1990StangGT]

Sorry I am such an idiot on this matter, I can put bolt on's all day but as soon as it comes to electronics I am not the greatest. So basically toss the test light and go get a voltmeter, then put the voltmeter on all the fuses to check the voltage? After all this checks out fine check fuseable links? I thought only fox bodies had these not the newer ones? And I actully yanked out all my fuses and replaced them with the right size ones? And if I do come across a fuse that does not light up with the voltmeter but fuse looks fine from there I just follow the diagram and check those wires? I am still a little confused help me a out a lil more like I said I am pretty retarded when it comes to electronics but I am on my way for that voltmeter.

 

[n0v8or]

Do you have an owners manual (fuse location diagrams on pages 111-115) for your car? If not, you can download one at the Ford Fleet site (I just did).
The URL is: https://www.fleet.ford.com/maintenance/owners_manuals/default.asp

First, get familiar with the voltmeter by measuring an ordinary AA or 9V battery. The meter selector switch should be set to one of the "DCV" or "DC volts" ranges. You can use a 2.5V or 10V rqange for household batteries, and probably the 50V scale for car measurements (unless there is a 25V scale, which would be better). "Scale", in this case, is what the meter reads when the needle is all the way to the right.
For vehicle measurements, the black probe is always connected to a good chassis ground, and the red probe used to check the voltage at both sides of a fuse. There are usually small openings in the back of fuses at both ends where you can contact the metal inside with the tip of your probe.

 

[1990StangGT]

Ok, now as soon as I check these and say a fuse looks fine but is not reading right on the voltmeter I can narrow this down to the problem right? After this I will do what with the wiring? Also you said the fuseable links are the last step to check well I did not think to check them becasue on my fox body they are labeled but I do not see any on my 99?

 

[ultrashock2112]

Ok, now as soon as I check these and say a fuse looks fine but is not reading right on the voltmeter I can narrow this down to the problem right? After this I will do what with the wiring? Also you said the fuseable links are the last step to check well I did not think to check them becasue on my fox body they are labeled but I do not see any on my 99?

The voltmeter isn't really too useful for testing fuses... This is how you can do it though: with the fuse plugged in measure the voltage on one side and then the other side (relative to ground, i.e. the black probe on the car's chassis) you should get the same reading (~12v) on both sides. If you measure the voltage with one probe on one side of the fuse and one on the other side, the reading should be 0V, if it is >0 you have a problem because there shouldn't be a voltage drop across a fuse.

You need to see where the power is "stopping". Use the voltmeter with the black probe on the chassis and start moving backwards. Go to the fuse that is supposed to be protecting the devices that aren't working, remove the fuse and measure the voltage on both sides, there should be 12V on one side and 0V on the other. If there is, then you know that the problem is somewhere between that fuse box and the device. You may need to get a look right up under the steering column to see the wiring in there.

 

[Jinx]

Did you pull the cigarette socket out? The connections on the back could have come loose or melted, possibly breaking the circuit.

 

[n0v8or]

Like Ultrashock2112 suggests, a logical approach is best. Here is how I would proceed:
Just pick one circuit to troubleshoot. If there is a common cause for most or all of your problems, it will be resolved at the same time. I would select the heater blower motor, because it draws a lot of current, passes through both fuse boxes, and the test points are fairly easy to access.
The motor is just behind the glove box. There should be 2 connectors, one for the speed control resisitors (4 pins) and one for the motor (2 pins).
First, with car off, use your meter to measure between the battery + post and chassis. This reading should be between 11V and 13V. This is your reference for future measurements.
Now, turn the key to "run" but don't start the engine. Turn the heater switch to heat and the blower speed switch to the highest speed. I will assume here the the blower is not running.
Probe both ends of fuse 24 (under dash fuse box) with the black probe at chassis ground. You should read approximately the same as the "reference" measurement on both ends of the fuse.
If only one side reads ~12V, and the other zero, that indicates a problem between fuse and blower. No reading on both sides indicates a problem betwen the fuse and battery, and the next step is to probe both ends of the three 40A Ignition fuses (under the hood). Two correct measurements means measure the voltage at the motor connector next (pull it of to probe the pins).
Next steps depend on the results of these.