First time had M&S flashing lights - new alt from Advance cured it, for 2 months.
Couple weeks ago, I cleaned the battery posts and added distilled water to battery, cured it.
They are on again, and I'm wondering if there is anything else I should check, clean, or replace battery cables & post connections before I go and buy a new battery.
Current battery is an Advance auto silver 600cca 750ca from PO that is 2 years old and "checks out" according to their system: 12.5v (down from 12.63 three months ago)

I just checked the trans fluid level and all is well, topped it off, and it still looks/smells brand new.

I don't want to just throw $100 bucks at a battery if it isn't the cause...do my connections look fine? Should I buy some new battery cables and post connections? FYI - I'd probably just get the Gold 34 series rated at 875 and 700cca for $100. I'm hoping it isn't my trans ECU, but I'd assume if it was it wouldn't "be fine" for months and weeks at a time?

Thanks!

 

Use a multi meter and see what your battery voltage is while the engine is running. Should be 13.5+ volts.

 

Clean terminals again - and while you have them off add some di-electric grease. It will keep them from corroding for a good while.

 

Is it throwing any codes?

 

I went through 2 AutoZone alternators in 1 year, then 2 Advanced Auto Parts alternators in 1 year.
Finally I settled on a used one, been good for a year now.

 

While you have the battery cables removed to add dieletric grease. Also put a pair of green and red felt washers under your cables on the battery posts. I added some to my battery. I heard they absorb outgasing from the battery and help prevent corrosion. I guess I will find out over time.

 

The only codes I have are 0154 and 0134, both front 02 sensors that I've been fighting.

I will try cleaning the posts and all connections and use some dielectric grease and see what happens.

Spike, unfortunately I too worry about the alternator, but so far no signs of it being bad.

Anyone else have any trouble with a "lower quality" battery? The readout had mine at 505cca out of 600...what voltage and amps are necessary for our high maintenance trans ecu's? I believe I've heard around 13-13.5v, not sure about amp.

 

The lights are not stupid in the first place, they know why they are on, you don't.
A disco requires 13.6 to 14.4 volts, any less and you have a problem. Bet you will find it was that cheap rebuild that has failed. There are very few companies that can/or do rebuild alternators correctly. Have your's tested, where you bought it, then order a new one from British Parts of Utah and get your money back for the used one.

 

Hah, I know, it's just easier to call the lights stupid then myself!
Thanks for the voltage requirements, I will get it checked again today. Assuming I should get it checked under load as well and should still be within that range...

 

Any auto parts store can test the charging system, usually for free.