Posted by Traveler on January 21, 03 at 10:52:01:
In Reply to: how to replace the positive bat. cable posted by rlra on January 21, 03 at 10:20:22:
Very difficult to measure with a meter due to access to the battery terminal, unless you have a dual terminal battery.
***Whenever you work on it, disconnect the negative terminal first.
You can try cleaning up the terminals again to see if the fast idle goes away. A small stainless steel brush works well. You can rinse off with baking soda solution to get rid of acid temporarily. Acid will have been stored in the rubber boot and possibly in the wire strands.
It will take 3 - 6 months for the corrosion to return bad enough so it won't start.
To change the cable, you will need access to the bolts on the starter. This may be worth a few bucks to a shop with a lift. I did mine in the driveway but it is a pain. The same cable will be connected to the alternator stud as well. It's probably only the positive side with the problem.
Here's the full description of what I think the problem is:
Here is the scenario: The + terminal on the battery becomes a bit resistive from temp cycling, squish of the lead spacer, and oxidation. + terminal resistance heats, cracking the battery case slightly. Small acid leak wreaks havoc with terminal corrosion, even though they look OK outside. Acid can even run down the starter cable and ruin the starter.
Owner finds the corrosion, cleans, and 1 of 3 things happen: 1.) same battery used; leak causes corrosion inside 6 months; same problem repeats. 2.) New battery installed, terminals cleaned but not modified: acid trapped in red rubber boot over terminal lugs causes corrosion to continue. 6 months later, + terminal is resistive and heats up again. New battery has + terminal area cracked and develops acid leak. Same problem. 3.) driver reads this message, no further problems.
I put in an Optima battery and it was high enough quality it didn't leak, but the heat was enough to start melting the yellow plastic on the top.
The Fix: Replace Battery and all battery cables. Alternatively, get out diagonal cutters and cut off the rubber surrounding the terminal lugs. You can leave a stub at the end of the cable, as long as the lug or eyelet is fully exposed. Clean the lugs with a wire brush and baking soda solution. You can replace the lead spacer slug with brass washers, or just clean it up with sandpaper. Replace the fastening bolt if it is corroded. Check that the OEM bolt isn't bottoming in the battery and not clamping the lug stack if the (squished) lead spacer is reused. You can discard the spacer and use a shorter bolt, or use a 1 to 1 1/2 inch long standard bolt screwed into the battery, with a nut on it to tighten against the lugs (brass preferred).
If the corrosion returns, acid has wicked into the cables and they will have to be replaced. I’ve seen battery acid travel down a wire over 10 feet on my truck.
If you change the cables and have a battery with top posts, consider changing to top post connections. Optima batteries with dual posts are what I recommend. They can’t leak acid because they are absorbed glass mat technology. Optimas can even be mounted upside down or on their sides.
If using an Optima, coating the terminals may not be needed. Optionally coat with protectant like Boeshield T-9 spray (from marine stores) or AMSOIL HD metal protector.
Possible side effects from intermittent terminals:
-Reduced life of alternator, fuel pump, starter, and second battery if equipped.
-Unusual behavior of the ABS, transmission, instrument cluster, and other electronics. Voltage gauge should read low if the terminal is resistive.
(Revised July 2002)
All IMHO from my experience. GM may have a different view.