I have a 2005 FX4, and the other day my battery died. Next day, got a new battery, but now my radio won't come on. I tested the leads, and it still gets primary power, but the remote turn on wire (light green/yellow if I remember correctly) does not get any power. If I jumper power to that pin, the radio will turn on. I've checked every fuse in the panel that could possibly be it, even a lot of them that couldn't, but I cannot find anything wrong. I don't know if there might be a relay or something that could control it, I also tried swapping out R02 accessory relay for one that I know works. Please help


Doug

 

There are 3 fuses for the radio.

F31 - 20A
F7 - A
F22 - 10A
- This is to the Del / acc pin on the radio via Light green w/ yellow stripe wire from the output of the accy delay relay.

Sounds like you want to check F22 while installed with a meter or test light to a known good ground and each side of the fuse.
- Need to have the key in the run or accy position when testing.

The PDF version of the owners manual show these, and it is easier to do a find in document for radio or audio than trying to read through all 50 some odd fuses in the paper copy.

 

I have checked all of those, and they are all OK. Although, for some reason, I am not getting any power to F7-5A.i have double and triple checked everything I can think of. Any ideas why that might be? Thank you for your help.


Doug

 

Owners manual page 226 ( PDF version )

7 5A* Radio (start signal)
- This means it is only hot in the start position.

If you checked both sides of F22 & F31 with a meter, while the key was in the run / assy position, and got + VDC on both pins, then something happened to the wiring.
- F22 leaves the fuse panel and is routed to the radio.

 

Actually, I didn't use a meter. I only used a test light. I will go back and check them with a meter. Incidentally, I also expected that F7 would only be powered in the start position, but my light didn't even show a blip when I tried it.


Thanks
Doug

 

If you got nothing from F7, it could be blown.

I would expect the test light to catch a crank cycle if you are probing the pin correctly while someone else turns the truck over.

The bad thing about test lights, is what is the voltage to turn on the light ?
- Can assume 12V or higher, but it might not be the case, meter shows the actual value.

Where are you jumpering the delay / accy lead to the radio ?

 

Ok, I checked using a meter, and I get a full voltage blip on both sides of F7 when cranking, but once running, it drops very low, and might even go slightly negative, if I'm doing it correctly. On F22 and F31, when the key is in the ON position, I get full 14V on both sides of these fuses. The other day, I jumpered from the large green with black stripe power pin to the light green with yellow stripe, and got the radio to turn on. Today when I tried it, it blew F31 fuse. I usually don't have any problems tracking down electrical problems, but I hardly ever use a meter, and this is really confusing me. I really appreciate your help SSCULLY.

Thanks
Doug

 

That is what I would suspect F7 to do, have + VDC in start, and once the key position is anything else, it is ground to nothing which would explain seeing - VDC on it ( it is hanging open, nothing real to use against ref / ground ).

Are you sure it was Green w/ black stripe or Black w/ light green stripe ?
- Black w/ light green stripe is to ground from terminal # 13 on the head unit connector C290A to ground G201.

Taking a somewhat quick view of the Cell 130, I did not find a Green w/ black stripe wire.

If you tested both sides of F22 as good, time to check for continuity from the light green w/ yellow stripe wire to fuse slot F22. should have < 100 ohms ( I would expect < 10ohms )
- Easiest to pull the fuse, one side is hot with the key in run / accy, the other is to the wiring harness.

 

Ok, I checked continuity between F22 and light green with yellow stripe, and it checked out fine. If I was checking resistance correctly, I was getting less than 1 ohm.

The large green with black stripe might be green with violet stripe. It is in pin location 1, and it is constant 12V, regardless of key position.

 

OK, so there should be + VDC on pin #2 light green w/ yellow stripe when the key is in the run / accy position by the testing you have done.
- radio problem then, if you did the testing above with those results.

Pin #1 is light green w/ Violet stripe wire, that is from Fuse #31.

 

So today I went back out and tried to check voltage at pin 2,after checking continuity on it yesterday, but today I can't get continuity on it, nor voltage. It appears that the slot in the fuse block might be loose. It looks like a nightmare to unbolt the fuse block and pull it out some though. As a last resort, would it cause a problem if I swapped pin 2 and the one adjacent, I think pin 14 that goes to vss, as it is also switched 14V source? I really don't want to tear into the harness behind the fuse block.


Thanks
Doug

 

VSS is a variable output, it is not always + VDC.
- that is how the speed volume works.

Unless one of the cheap add a circuits were shoved in there, it should not be bent.

If you want to try that, you can go to autozone and get one and put it on the output side of the fuse slot, and see if it tightens it up.
- That is if you are sure that is the issue.

the other thing you can try is to slightly pry the female terminals together, again if you are sure that is the issue.

Might want to confirm that is the problem by inserting a filed down male spade terminal in there.
- Use the fuse blade as an example.

BTW : While you are going back and checking things, did you check that the fuse to a known good ground has + VDC on both pins on the back of the fuse ?

 

Actually, I did put an add a fuse in there to turn on my amp. I did that a long time ago though, and have never had any problems with it until now. It's just wierd that I'm having a problem now, after my battery died. Another strange thing is that If I take it out with no fuse in there, I cannot get a continuity ring, nor a positive voltage signal, but when I put the add a fuse back in there, I can get positive voltage on both sides of both fuses, AND it's still powering my amp. I guess that probably because the only output now is going from the hot side of the fuse location straight to the amp to complete the circuit.