loose battery cables

[bikemikey]

After posting a few threads on loose battery cables, I thought I had my problems solved, wrong! I got mad and changed out the battery to a post system. I bought a new interstate battery with both side and upper posts, I used raptor 24K post terminals with allen screw downs for the cables. I took the car out for a spin, everything was fine until I put about 15 miles on the car. Then the voltage starting jumping around again, then the battery light starting to go on and off. I pull over and checked the battery connections, they were good and tight. Keep in mind I've gone through all the battery connections under the hood , it has a rebuilt alternator. I got to thinking, it seems like the car runs fine until the computer resets itself, I'm wondering If I could have a problem with the BCM. Could anyone tell me how the BCM is grounded, it there a ground wire on the case, maybe it's loose. I looked at the wiring diagram, it shows a ground wire coming out of the BCM, but I don't know if it is on the outside of the case or internally. Also, are there any strap grounds under the car, some cars have them? I also think this is where the lumpy idle comes from that I talked about in previous posts. Appreciate any help you can give me. Thanks, Mike.

[Guest Mc_Reatta]

There are several key junction posts under the hood that ground all the key dash components and one that supplies power to key systems. There is also one on the engine head by the PCV valve not shown.

Here's a write up on them:

http://reattaowner.com/roj/component/content/article/62-electrical-system/other-electrical/224-ground-terminals-junction-box-location

[D-a-n-i-e-l]

After posting a few threads on loose battery cables, I thought I had my problems solved, wrong! I got mad and changed out the battery to a post system. I bought a new interstate battery with both side and upper posts, I used raptor 24K post terminals with allen screw downs for the cables. I took the car out for a spin, everything was fine until I put about 15 miles on the car. Then the voltage starting jumping around again, then the battery light starting to go on and off. I pull over and checked the battery connections, they were good and tight. Keep in mind I've gone through all the battery connections under the hood , it has a rebuilt alternator. I got to thinking, it seems like the car runs fine until the computer resets itself, I'm wondering If I could have a problem with the BCM. Could anyone tell me how the BCM is grounded, it there a ground wire on the case, maybe it's loose. I looked at the wiring diagram, it shows a ground wire coming out of the BCM, but I don't know if it is on the outside of the case or internally. Also, are there any strap grounds under the car, some cars have them? I also think this is where the lumpy idle comes from that I talked about in previous posts. Appreciate any help you can give me. Thanks, Mike.

Pull your alternator and have it tested. I have had a few rebuilts end up bad. Also clean the ground to the engine and check for bad connection to the alternator (by multimeter while shaking pulling and pushing on all connections.

[bikemikey]

Pull your alternator and have it tested. I have had a few rebuilts end up bad. Also clean the ground to the engine and check for bad connection to the alternator (by multimeter while shaking pulling and pushing on all connections.

Okay, I'll check everything again. Do you think it would be okay to put a jumper on G100 and G102 and ground it to another place, it probably wouldn't hurt , am I wrong on that one. I know sometimes you have to be careful with the wire size. Thanks

[bikemikey]

Okay, I'll check everything again. Do you think it would be okay to put a jumper on G100 and G102 and ground it to another place, it probably wouldn't hurt , am I wrong on that one. I know sometimes you have to be careful with the wire size. Thanks

Well I finally found out what the problem was with the battery cables and connections. I had a bad output lead that comes off the alternator then goes straight to the battery. Even though it checked with an ohm meter, their must have been some corrosion in the cable. I replaced the 6 gauge wire with a bigger 4 gauge wire for better flow. The volt meter now holds steady with minor fluctuations , it does not nose dive like it used to when revving the engine. The cables where cold to the touch which tells me there is no resistance or what I think they call impedance. It also helped out the idle.

Anyway, I thought I'd pass this along, hope it helps someone. Thanks everyone.

[Barney Eaton]

Thanks for posting your finding, it may help another Reatta owner in the future

[wws944]

It is a well-known problem with certain side terminal batteries that the bolt could 'bottom out' and feel tight, yet the terminals would still be a little loose. With the poor contact, heat would build up, causing the case around the side terminal to warp slightly and acid could weep out. Once on the cable, acid can wick through the wire inside the insulation - eventually corroding the wire into dust. It can even take out the alternator due to the intermittent connection.

Many years ago, I had this exact situation in my Suburban. Made a real mess in the engine compartment and I had to replace some of the cables. I have seen some Reatta owners post similar problems, and Ronnie even has a page at ROJ on it. I bet if you cut open your bad wire, the bad spot would be on the battery side.

It is one reason why I tend to buy AGM batteries nowadays: no free acid to leak out.

[TexasJohn55]

It is a well-known problem with certain side terminal batteries that the bolt could 'bottom out' and feel tight, yet the terminals would still be a little loose. With the poor contact, heat would build up, causing the case around the side terminal to warp slightly and acid could weep out. Once on the cable, acid can wick through the wire inside the insulation - eventually corroding the wire into dust. It can even take out the alternator due to the intermittent connection.

Many years ago, I had this exact situation in my Suburban. Made a real mess in the engine compartment and I had to replace some of the cables. I have seen some Reatta owners post similar problems, and Ronnie even has a page at ROJ on it. I bet if you cut open your bad wire, the bad spot would be on the battery side.

It is one reason why I tend to buy AGM batteries nowadays: no free acid to leak out.

Agree on all counts. I would also add that once the acid gets inside the cable insulation it will continue to cause problems long after the leaky battery is replaced. I am continuing to have that problem on my side terminal setup. I have put off replacing the cables but will have to sooner or later. The acid continues to gas and contaminate the connection at the battery and I frequently have to remove cable, scrape and clean and douche with baking soda solution. The problem is way up in the cable insulation and impossible to get to.

Another problem with the side terminal setups is that they frequently have 2 positive cables. One goes to starter and the other feeds the electrical system. That can cause all kinds of crazy symptoms depending on which of the 2 is not making connection. It may crank up and drive all day but not charge the battery or it may power accessories but not crank the engine...Sorry setup if you ask me.

[bikemikey]

Agree on all counts. I would also add that once the acid gets inside the cable insulation it will continue to cause problems long after the leaky battery is replaced. I am continuing to have that problem on my side terminal setup. I have put off replacing the cables but will have to sooner or later. The acid continues to gas and contaminate the connection at the battery and I frequently have to remove cable, scrape and clean and douche with baking soda solution. The problem is way up in the cable insulation and impossible to get to.

Another problem with the side terminal setups is that they frequently have 2 positive cables. One goes to starter and the other feeds the electrical system. That can cause all kinds of crazy symptoms depending on which of the 2 is not making connection. It may crank up and drive all day but not charge the battery or it may power accessories but not crank the engine...Sorry setup if you ask me.

That's a lot of good information there. I have a question, if an engine had this impedance, resistance problem like I had, would it cause the spark plugs to foul after awhile and maybe a little extra carbon that would not be there if it were not for this problem? I thinking about pulling a spark plug and check it out. The idle problem I used to have is now a lot better, when I get a chance I think I will blow out the engine on the freeway , since it is getting the right voltage maybe the idle will smooth out even better. Just a thought, what do you think? Thanks

[TexasJohn55]

With electronics it is hard to discount anything, running rough or dying would not surprise me. Carboned plugs, maybe but I doubt it.

[Ronnie]

There are several key junction posts under the hood that ground all the key dash components and one that supplies power to key systems. There is also one on the engine head by the PCV valve not shown.

Here's a write up on them:

http://reattaowner.com/roj/component/content/article/62-electrical-system/other-electrical/224-ground-terminals-junction-box-location

I will try to get a photo of that ground location and add it to the tutorial.

[wws944]

That's a lot of good information there. I have a question, if an engine had this impedance, resistance problem like I had, would it cause the spark plugs to foul after awhile and maybe a little extra carbon that would not be there if it were not for this problem? I thinking about pulling a spark plug and check it out. The idle problem I used to have is now a lot better, when I get a chance I think I will blow out the engine on the freeway , since it is getting the right voltage maybe the idle will smooth out even better. Just a thought, what do you think? Thanks

Cars like to be driven. Can't hurt.

BTW, 'impedance' is used in AC circuits. The battery/alternator circuit is DC - so resistance is the correct term.