Has it ever thrown a code.
Sounds like a grounding issue.

 

Thank you for replying.
Interesting you asked that. Right before this whole mess started, in the process of me towing another car, my car did not want to start after I turned it off. Fortunately since the tow was on hand we had it towed to an AutoZone and they let me borrow the code reader since the check engine light was on.
As soon as we plugged it in the code reader immediately showed "wait" and something along the lines of "system reset" came next and we started the car on a whim and it started right up with no check engine light.

A grounding issue... is that with the battery terminals and cables?

 

So, since then you haven't put a scanner on it again? Wondering if it's an ECM issue and if you could get a scanner on long enough to see the code history, doesn't have to be an active fault. Might give ya another diagnostic path to follow.
I'm thinking engine grounding wires that sometimes will attach to a fender well from say the intake manifold.
The smaller gauge wires, could even be the ground wire for the ecm.
Is your battery voltage staying consistent ?

 

I'll know more on Saturday since I work tomorrow night. I'm having my brother bring his code reader (I don't have one yet) and multimeter to to be double sure. The multimeter I have is quite old but its been reliable so far.

As of now I have the battery on a slow charge since it was reading a bit low (11.9). It's a new battery but with all the starting and whatnot I'm assuming it's just not been able to charge properly.

This has definitely been a head scratcher for sure. I'll update this post on Saturday with any codes and if the battery stays around the 12.5 and hopefully get a solution. Thanks again for letting me know about other possible issues and have a goodnight!

 

I'll know more on Saturday since I work tomorrow night. I'm having my brother bring his code reader (I don't have one yet) and multimeter to to be double sure. The multimeter I have is quite old but its been reliable so far.

As of now I have the battery on a slow charge since it was reading a bit low (11.9). It's a new battery but with all the starting and whatnot I'm assuming it's just not been able to charge properly.

This has definitely been a head scratcher for sure. I'll update this post on Saturday with any codes and if the battery stays around the 12.5 and hopefully get a solution. Thanks again for letting me know about other possible issues and have a goodnight!

I don't think the code reader will tell you anything related to a no crank condition (unless you have a smart key system) your multimeter will be of more use in trying to troubleshoot a no crank condition.
I know you said you have a new battery- it is worth making sure that both the battery terminals and the connectors are clean (not oxidized) and tight, and that both cables are in good condition and the Negative cable has a good clean chassis ground.
With your meter check to see if you get a steady 12v at starter large terminal (that cable comes right off the battery and will dip somewhat when you crank), and 12 volt at the smaller terminal when you crank.
If the voltages are ok so far and it still does not crank you got a bad starter.
If either of the voltages are not there when you crank, you will have to trace back thru the wiring, connectors and switches to find were you lose it.
If you are interested in getting the diagram see my signature.
HTH
JerryR

 

Agreed , head scratcher but you'll figure it out!

 

Hello! I'm back to do a bit of an update.
Right so the code reader route was a dud. YJerryR was right, I didn't get a code, infact I got no codes.
The battery terminals and connectors are clean, I hooked up my multimeter. It may be off a little bit but I received a constant 12.6 and although my car doesn't crank at all when we attempted the battery would drop to 12.3.

The next step was to check with a circuit light tester. I focused on the Starter cables first. (Since the starter is new as well and had it checked to be sure). Well I did not a light on the actual starter plug harness. I did get a light on the other cable.

Just to be sure since I also I bought new Starter Relay. I checked in the area where it goes (I don't know what that is actually called. Is it called junction?) I got a light on all but one. Even when attempted to crank. I attached and marked the best I could from a phone.
Now while attempting to crank I checked the starter plug on the harness and there was light. But without attempting crank there was no indication of power.
At this point I feel it may be the plug harness but I don't know. Any tips or suggestions so I can narrow it down more?

 

Hello! I'm back to do a bit of an update.
Right so the code reader route was a dud. YJerryR was right, I didn't get a code, infact I got no codes.
The battery terminals and connectors are clean, I hooked up my multimeter. It may be off a little bit but I received a constant 12.6 and although my car doesn't crank at all when we attempted the battery would drop to 12.3.

The next step was to check with a circuit light tester. I focused on the Starter cables first. (Since the starter is new as well and had it checked to be sure). Well I did not a light on the actual starter plug harness. I did get a light on the other cable.

Just to be sure since I also I bought new Starter Relay. I checked in the area where it goes (I don't know what that is actually called. Is it called junction?) I got a light on all but one. Even when attempted to crank. I attached and marked the best I could from a phone.
Now while attempting to crank I checked the starter plug on the harness and there was light. But without attempting crank there was no indication of power.
At this point I feel it may be the plug harness but I don't know. Any tips or suggestions so I can narrow it down more?

I assume that the constant 12v you found is on the heavy cable and if you did not get 12 v on the the harness connector(the thinner cable), that indicates that the (new) starter relay is not operating.
the following is based on what I see on my 2009 (same gen as yours) and what I see in the ESM (even though the ESM does not exactly represent what i see in the car)
Pull out the starter relay and look at it's socket., the contacts are arranged like the letter T.
The cross bar from left to right are pins 1 & 2 And the pins on the tail are from top to bottom 5 & 3 (at least on my car -visually, I did not make any measurements to verify).
NO key in the ign.
With your multimeter set to OHMs on the lowest resistance scale, 1 probe on chassis ground the other probe on pin 2
You should read VERY close to 0 Ohms. If ok...
Next set your multimeter to measure 12volt, 1 probe on chassis ground the other probe on pin 5, try to crack. should be 12v, tell us what you find.
Next, leave the 1 probe on chassis ground & move the probe from pin 5 to pin 1 try to crank, should be 12v, tell us what you find.
HTH
JerryR

 

Thank you for replying. I took out my battery to make room to do what you suggested with the starter and found these cables. They have clearly disintegrated at some point. But I have no idea what they are for. Do you know what they are? And would that also effect the car not starting?

 

Good find.
In the picture that shows the frayed wire
I don't know what they are except that they are ground cables that must to be either repaired or replaced!!.
and if I am not mistaken, at the Bottom center of the picture also shows the bolted remnants of a wire eaten away by corrosion that you will need to find where it originally came from.
The wire shown in the other picture (bolted to chassis)-while it shows some signs of oxidation is probably OK, but I would unbolt it clean the area and the underside the eyelet with emery cloth.

"I realized you meant check starter relay pins afterwards not the actual starter but still it was an unexpected find".
What I referred to was the relay socket in the fuse /relay box- Not the relay itself.
HTH
JerryR

 

I realized you meant check starter relay pins afterwards not the actual starter but still it was an unexpected find.

 

Hello, I'm sorry for replying a couple days late, I've had a few tough overnight shifts. Finally have the next few days off. Well i checked the ohms and I hope I did this correctly but on pin 2 I got 9.4.

On pin 5 the highest I got on volts was 10.5v for a sec before dropping to 0.

On pin 1 the highest it went was .46v

I guess I have an issue with the socket?

 

Hello, I'm sorry for replying a couple days late, I've had a few tough overnight shifts. Finally have the next few days off. Well i checked the ohms and I hope I did this correctly but on pin 2 I got 9.4.

On pin 5 the highest I got on volts was 10.5v for a sec before dropping to 0.

On pin 1 the highest it went was .46v

I guess I have an issue with the socket?

I doubt you have a problem with the socket itself.
Before you continue...
I should have emphasized...
While the frayed wires may still be able to provide a ground they may represent high resistance and should be replaced( or at least VERIFIED that they still provide low resistance to ground).
A BIGGER DEFINITE problem is the eaten away cable whose remnants are shown at the bottom of the picture.
You have to find where it came from and repair that.
In addition, I have to apologize. In my previous post where I described the relay socket pins and their positions - I was wrong in identifying Pins 1 & 2 (I wrote from left to right pins 1 & 2).
I took another look at the diagram, and verified by measurement on my car. and the correct numbering is from Right to left pins 1 & 2, but remember! this is in my car (2009)based on looking at the relay/fuse box, The start relay is at the top row of the box towards the fire wall 2nd in from the right,(no relay in the right most position) on your car(2007) the box might be oriented differently.
Fix the wires before you attempt to continue trouble shooting because they may be the reason for the no crank problem.
HTH
JerryR

 

Many people on here are way more knowledgeable than I am, but I’d probably take care of those ground wires that are all frayed, and especially the one that looks like it is no longer connected to anything. Before replacing anything else or messing with connectors, since those ground wires really need to be fixed anyway, I think that would be the first thing to look at. Just my opinion.


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Hi, yes YJerryR said to repair or replace but at this point I think just replace since it's mostly gone one end. I'm just having trouble finding a replacement cable. I understand it's a grounding cable but is it any grounding cable or a specific one?

I feel though even if I just replace that cable the car will be in the same way. Although properly grounded going fowards.

 

Unlike old Rolls Royce there is nothing in the alternator circuit that is part of the crank circuit. Evening with the alternator out of the car and the belt off the engine if all of the grounds are hooked up and the battery is good and cables are clean it should crank and start and throw a code alt/charging code.

I think you have a wiring issues based on what you are describing.

 

My wife had a Buick LaSaber that would shut down going down the high way at 55mph and then randomly restart.

First I cut opent he battery connector since GM has that stupid side post with multiple washers inside sealed in plastic. Full of corrosion. Then I started cutting back the main battery power cables only available from dealership ran all the way across the engine bay something like 22 feet one piece and expensive as could be no part store carried that main piece just shorter splices. I had to cut back 6 to 9 feet before I found fresh shinny copper wire it was all green and corroded. I did it in one long single cut so I could save the cable insulation. I scrubbed it all out with backing soda and dawn dish soap and rinsed with garden hose. Let it sit in the sun to dry for 2 days taking inside before sun set so no dew would form on it. I breased it all up with moly-ep grease because that is what I had on hand. I then wiped all excess off and folded the insulation back up around the copper wire. I applied 2 layers of 3M electrical tape to everything and put it back in the conduit. Never had another problem again. Just to cover all my bases I took the main power dist. bus out of car flipped it upside down with all the wires in place and spray it with DeOXIT. I then took all the fuses out and relays out and put them in and out about 20 times each and again sprayed it all with DeOxit. Then sprayed the bottom with silicone spray and called it good.

Never had another issue again and never had the typical GM gremlins after that either!

 

Wow you went through all that? Well I'm glad it was worth it in the end if the car ran with no issues!
I see at this point that it's most likely electrical and I am going to have to strip and clean everything at this point. Plus replacing that one grounding cable. Or it may be the socket where the starter relay is... or the starter plug cable....

After the new alternator was put in, the car did start. The problem was that after the first initial start it didn't want to start again

 

At the time no aftermarket harness was available just small short chunks of it. The dealership wanted a few hundred I think $400+ so I did what I had to and it worked great compared to the $400 they wanted.I just recall it was about 1/3 the price I paid for the car used.

 

Update!!

After 1.5 month of banging my head against the wall with this car... it's finally running again!!!

Thank you all for your suggestions and tips!

After the last post we ended up just going throughout the car section by section just checking things through and cleaning it up.

At the end, we replaced two fuses that are below the steering column. Fuse 8 & 9 because not only did they looked like they were removed previously and were horribly crushed but they were also the only two that I had difficulty getting a reading on. Coincidentally while both fuses deal with the multiport fuel injector system fuse 8 also deals with the starter system.

After that, we also ending up making our own 3 way grounding cable after not successfully finding one exactly like the one we had. We put the new cable in and it started right up!

However it didn't want to start up again and at that point we exchanged the new previous starter to another. ( I had the hunch that I bought a dud starter as well) and now the car is starting up with no issues!


In short to get to this point that parts in order...

Replaced alternator

Replaced alternator fuse (break head trying to figure out how to find and replace)

Replaced starter relay

Replaced starter

Replaced fuse 8&9 under steering column

Replaced grounding cable from transmission to lower chassis to upper chassis.

Re-replaced the starter (good thing for warranties!)



All in all this has been an experience just to mostly figure out that the main issue? Was most likely the grounding cable and starter from the beginning.

 

Congrats! Glad it is up and running!


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