Negative Terminal Disconnect?

[The Insomnimaniac]

I’m a pure novice/beginner to working on my car. Im replacing the canister purge valve because I threw a CEL. The YT video I watched said to disconnect the negative battery terminal before starting. I started doing that only to discover that I can’t even get it loose enough to remove the terminal. I can only get it to wiggle side to side. Tried to retighten and it won’t tighten either. Long story short, do I have to disconnect the negative battery terminal to do the replacement or could I relatively safely go without?

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[ORRadtech]

Disconnecting the battery is not an absolute must. It's mostly to prevent accidentally shorting out something important. An accidental short could damage wiring and/or computer modules.
Having said that I personally wouldn't want to take the chance.
More importantly however, you need to find out what's going on with that negative battery cable! That is a must! Loose battery terminals can cause charging issues, starting issues, wiring issues due to excess heat and possibly a fire hazard.
Fix it, seriously, fix it.

 

[The Insomnimaniac]

Disconnecting the battery is not an absolute must. It's mostly to prevent accidentally shorting out something important. An accidental short could damage wiring and/or computer modules.
Having said that I personally wouldn't want to take the chance.
More importantly however, you need to find out what's going on with that negative battery cable! That is a must! Loose battery terminals can cause charging issues, starting issues, wiring issues due to excess heat and possibly a fire hazard.
Fix it, seriously, fix it.

Thanks for replying! No worries on the battery… it’s going to more experienced hands tomorrow. I noticed some crap around the terminal. Is this corrosion or something else?

 

[ORRadtech]

Corrosion. Not a serious amount but corrosion none the less. Nothing a stiff brush and a baking soda solution can't fix.

 

[The Insomnimaniac]

Corrosion. Not a serious amount but corrosion none the less. Nothing a stiff brush and a baking soda solution can't fix.

That’s what I figured. Could this amount of corrosion be the cause of that terminal being stuck though?

 

[Farkel]

This might help with the clamp conundrum -


A couple of suggestions:
Any time you want to disconnect the battery, just remove the ground wire at the strut tower. You'll see that it comes directly from the negative battery terminal clamp.
If you want to prevent corrosion at the terminal(s) forever, get an AGM battery.

 

[ORRadtech]

Hard to say without being hands on. Looking at your pictures I'd say maybe. Sometimes the clamp just deforms the lead post a small amount. But it can be enough to make it difficult to remove.
Also, which bolt did you loosen? The one to remove the clamp is the one beside the clamp, not the one attaching the cable.

 

[Ozcraig]

Hard to say without being hands on. Looking at your pictures I'd say maybe. Sometimes the clamp just deforms the lead post a small amount. But it can be enough to make it difficult to remove.
Also, which bolt did you loosen? The one to remove the clamp is the one beside the clamp, not the one attaching the cable.

I second this. On mine recently I found that the lower "jaw" of the negative terminal had slightly deformed the battery post. I could spin it but not lift it off. Unbolted the whole negative terminal clamp and the positive and lifted the battery out so that I could gently lever the negative clamp off the post. It had sort of bitten into the lead post. Much easier to sort out on the bench than in the car.

 

[S550HPP]

Just loosen it up, put a large flat heat screwdriver in middle of clamp twist to spread it, keep wiggling it'll come loose. Wire brush the dialectic grease on port battery posts.

 

[G.T.]

Yup, I'd try as mentioned above.

Loosen the clamp and it should lift straight off.

If not, wiggle the clamp while lifting up.

If it still wont come off, then spread the loosened clamp a bit with a flat blade screwdriver while wiggling and lifting up.

If a job calls for disconnecting the battery, I usually do so. I've experienced fried modules and parts without doing anything electrically damaging so they can sometimes be sensitive or I am just unlucky with that kind of work lol!

 

[Garfy]

Yup, I'd try as mentioned above.

Loosen the clamp and it should lift straight off.

If not, wiggle the clamp while lifting up.

If it still wont come off, then spread the loosened clamp a bit with a flat blade screwdriver while wiggling and lifting up.

If a job calls for disconnecting the battery, I usually do so. I've experienced fried modules and parts without doing anything electrically damaging so they can sometimes be sensitive or I am just unlucky with that kind of work lol!

Being that the canister purge valve would never be activated by the PCM unless the engine was in operation, it's probably ok to replace it without disconnecting the battery. There's a lot of parts that the repair info always say to disconnect the battery before doing such-and-such, but if you know how the system works, many don't need to have the battery disconnected. That being said, it doesn't mean there's no power/voltage on the supply side so you must be sure to never get the lead on the connector touching ground at any time. In most cases, you'd have to try really hard to be able to do that, but ordinarily it won't contact ground so it should be fine. I've replaced sensors and solenoids/valves without disconnecting the battery but they were all inactive components. For liability reasons a lot of manuals say to disconnect the battery anytime you do anything on an electrical component. In my 44+ year career, I've only damaged 1 or 2 modules for other reasons than not disconnecting the battery and muttered to myself for being so stupid.

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