Fuse box under hood only the top half has any power going to it

Tiny
BTRIMM1982
  • MEMBER
  • 2006 PONTIAC GRAND PRIX
  • 3.8L
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 160,000 MILES
Okay, well, it all started with a bad starter. Replaced and the car would not start. Chased bad ground connections. All I found was some corrosion. Cleaned it up, still nothing. Lights come on gauges move turn the key to start everything shuts off. Changed ignition switch. Kept old lock cylinder. Nothing still the same. Lights, gauges, turn over the key it all shuts off. Checked the battery it read 11.9 fully discharged. Put the new battery in same thing back to square one. Started checking fuse box under the hood with a multimeter and only the top half has power to it. Did notice some yellow discoloration on four of the relays. Couldn't tell you which ones at the moment. I had to walk away for the evening very frustrated. Please help make sense of this. Thanks in advance.
Sunday, May 29th, 2022 AT 6:16 PM

12 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,114 POSTS
Hi,

What you describe sounds textbook to a weak connection normally at the battery itself. Are the terminals in good condition, clean, and tight?

Take a look through this link:

https://www.2carpros.com/articles/everything-goes-dead-when-engine-is-cranked

Also, I attached a pic of the fuse box. Can you let me know which fuses are not getting power? (See pic 1)

Let me know. I can work through the power distribution schematics to see if there is a specific point to test. However, it honestly sounds like a weak connection.

Don't laugh but try this. When it's dark, open the hood and have a helper turn the key to start the vehicle and see if you notice any spark which could happen at a weak connection. I know it sounds crazy, but it may point you in the right direction.

Take care and let me know what you find.

Joe

See pic below.

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Sunday, May 29th, 2022 AT 9:12 PM
Tiny
BTRIMM1982
  • MEMBER
  • 8 POSTS
Thanks Joe it would be something easy.
I will let you know. Here's that picture with the fuses that are out.
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Monday, May 30th, 2022 AT 6:04 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,114 POSTS
Hi,

Looking at the fuses without power, it seems the fuse box itself has failed. There are a few of them which receive power from relays, but they are good.

I attached the power distribution schematics below. Take a look through them and let me know your thoughts.

Let me know if you have other questions.

Take care

Joe

See pics below. Note: The schematics were three pages. I had to cut each one in half to make them readable for you. I did overlap them.
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Monday, May 30th, 2022 AT 7:41 PM
Tiny
BTRIMM1982
  • MEMBER
  • 8 POSTS
Hey Joe, Brandon again. I believe I have conquered the issues from above. Now I have two warning lights in the middle dash. First says service theft deterrent system, followed by starting disabled due to theft system. I looked up a few things and found the procedure for the second message. With exception. By my gauges, my anti-theft light is not on, also when my girlfriend purchased the vehicle it only had one key no fob so I'm not sure how to service theft system without the fob? There are a couple pictures to show what I'm looking at. I can't get a picture of the service theft system message yet due to in process of trying to get the car to relearn the key. Almost there, I can feel it!
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Monday, May 30th, 2022 AT 7:43 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,114 POSTS
Try something. Turn the key to the on position and allow it to stay there for approximately 10 minutes. See if the light turns off and the vehicle stops.

Let me know.

Joe
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Monday, May 30th, 2022 AT 8:18 PM
Tiny
BTRIMM1982
  • MEMBER
  • 8 POSTS
The light or message stays on. It's the light on, in the middle of the dash. The security light itself hasn't come on yet. That's the one by the gauges. I tried the 10-minute thing several times. Tried doing it for a half hour 10 minutes each time and nothing. The other message says theft deterrent needs serviced. All the articles I found include a key fob. Which we never got when the vehicle was purchased.
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Monday, May 30th, 2022 AT 8:55 PM
Tiny
BTRIMM1982
  • MEMBER
  • 8 POSTS
Hey Joe, sorry to keep bugging you. I'm at my wits end here and have been searching for all day on the web for a clear answer and there isn't one. I have watched some sketchy videos on this stupid thing. Anyway. Okay, so after getting the cables and connections cleaned up and secured properly. I got 12.6 on the battery and the cables coming off the battery. When I try to start this thing mind you I have only one key and no fob. The key has pk3 on it. I get the starting disabled due to theft deterrent message. I went through the 30 35-minute procedure at 10 minutes a piece making sure I followed the time frame. (Also, I have to mention that on my gauge panel, RPM, speed etc. It does not show the security light. The only thing showing this error is in the middle display. I can't do anything with the display, none of the buttons change what's on the screen.) After I do this process for approximately 30 minutes or so when I try to start the vehicle it does not start, I turn the vehicle off and leave it in the off position I let sit there about 10 seconds and I pulled the key out. On the middle display after the key is removed it says service theft deterrent system then goes blank. I'm at my wits end here I've dropped a lot of money in this thing and I don't want to have to take this thing to the dealership because I don't have the spare money to go through their process matter of fact this thing is broke me. Also know that on the lock cylinder itself there's a black ring not the one that says off on accessory start but a smaller one underneath that. Is this the transponder for the vehicle? Or is it the part that is around the negative cables with a harness plugged into it? I saw that a lot in some videos, but no one touches base on this. Like I said I'm at a point where it's going to get a sign on it stating doesn't start due to. And tape the signed title to the back of the sign and announce highest bidder and let all 2 of them that will take it, go with it for $300.00. I can't put another dime in it. If there's anything that may shed a little more on my problem. It would be greatly appreciated! Have a good evening!
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Tuesday, May 31st, 2022 AT 6:17 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,114 POSTS
Hi,

Hang in there. We'll get it fixed. I just spoke with the site owner regarding this. He is excellent with GM vehicles. If indicated, it could be the positive battery cable.

Here is what I need you to do. You will need a helper. On the starter motor,
locate the main power supply from the battery to the starter. The main wire is red in color and should have 12v at all times. Confirm that is the case. If it is, have a helper turn the key to the start position while you watch for a voltage drop to the red wire.

I attached the wiring schematic below for your reference.

If there is no change in the voltage to the red wire, have your helper turn the key to the start position again and check to see if there is 12v to the purple wire. This wire should only have power with the key in the start position.

Here is a link you may find helpful:

https://www.2carpros.com/articles/how-to-check-wiring

Let me know what you find.

Take care,

Joe

See pics below. Note: The schematic was only one page. I had to cut it in half to make it readable for you. I overlapped the two pics so you can follow from one to the next.
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Tuesday, May 31st, 2022 AT 9:15 PM
Tiny
BTRIMM1982
  • MEMBER
  • 8 POSTS
Okay, I can definitely do that. Let me make sure I understand. The red wire from battery to starter should have 12v and stay at 12v when the key is turned. The purple should only have 12v once the key is turned to on position? If it doesn't?
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Tuesday, May 31st, 2022 AT 9:28 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,114 POSTS
The purple wire only should have 12v with the key in the start position. Once you allow the key to return to the run position, power to the purple wire should not exist.

As far as the 12v to the heavy gauge red wire, we are questioning if the power is lost. If the start would actually engage, the voltage would likely drop to approximately 10V just due to the draw from the starter. However, in this case, we are checking to see if drops to 0v or very low voltage.

Let me know what you find or if you have questions.

Take care,

Joe
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Tuesday, May 31st, 2022 AT 9:49 PM
Tiny
BTRIMM1982
  • MEMBER
  • 8 POSTS
Okay, will do. I might be missing something but what does this have to do with servicing the theft deterrent or getting theft deterrent to clear so I can start it. I get what you're saying about the voltage part, but will it prohibit the car from going through the theft deterrent to activate the starter and the fuel pump? I'm not trying to question what you are telling me I'm just trying to make sense of all of it in the bigger picture of things. Plus, I'm tired and need to get some sleep. I had enough of this Pontiac for the day. Have a good evening. I will let you know what comes over the test on the two wires. Thank you very much for your help!
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Tuesday, May 31st, 2022 AT 11:01 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,114 POSTS
Hi,

Interestingly, I had the site owner read the issue from your post for his input. He replied to me within five minutes indicating this was a likely cause. Based on what he told me, if the positive cable to the main lug on the starter shorts, it sets that light. I've been in the business for pushing 40 years and never heard of it, but he took over the family shop from his father, so I suspect if you add both of their years together, they have a lot more than me. LOL Plus, he is really a great mechanic.

Take care. I'm hoping it is something this simple.

Joe
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Wednesday, June 1st, 2022 AT 7:56 PM

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