Grounding Points?

[marshallpre1]

Does anyone have a diagram showing all the locations of the grounding points for the 8th gen?

Thanks

[marshallpre1]

bump

[Banana_Boat]

Milk, Milk, Lemonade, around the coner fudge is made?

[fishexpo101]

Vamp used to have one on his site - but I believe it is down. Might be able to find ones floating around on the net. Should be able to trace back your existing grounding points on the engine - to get a diagram, need to find a Toyota Factory Service manual.

[marshallpre1]

Originally Posted by fishexpo101

Vamp used to have one on his site - but I believe it is down. Might be able to find ones floating around on the net. Should be able to trace back your existing grounding points on the engine - to get a diagram, need to find a Toyota Factory Service manual.

I have a feeling the reason my corolla isn't starting (consistently) is because of my ground points. My haynes manual is useless. I just didn't want to take a bunch of things apart only to not need to. Sometimes they are hiding all over the place!

[fishexpo101]

There are hidden chassis ground points - can be tough to get them all. You are correct that poor chassis grounds can cause driveability problems. I would first check for ground loops - the first indications of chassis ground problems. No sense ripping all the wiring off, if there isn't a problem in the first place.

Easiest way to check for ground loops - you need a high impedance multimeter. Set the voltage scale to the millivolt range and see if there is any voltage potential between the ground on the battery and various points on the chassis and engine (touch the clean metal bits). You should read zero millivolts. Any voltage that shows up - means there is a ground loop present. Current flowing between two points that should be at the same potential, can cause all sorts of electrical problems.

Starting consistency is another matter - could be cause by a number of things. How is the car not starting consistently? Is it not cranking? Not catching or having a hard time catching? How does it run otherwise? Idle quality, fuel economy changes?

[marshallpre1]

Originally Posted by fishexpo101

There are hidden chassis ground points - can be tough to get them all. You are correct that poor chassis grounds can cause driveability problems. I would first check for ground loops - the first indications of chassis ground problems. No sense ripping all the wiring off, if there isn't a problem in the first place.

Easiest way to check for ground loops - you need a high impedance multimeter. Set the voltage scale to the millivolt range and see if there is any voltage potential between the ground on the battery and various points on the chassis and engine (touch the clean metal bits). You should read zero millivolts. Any voltage that shows up - means there is a ground loop present. Current flowing between two points that should be at the same potential, can cause all sorts of electrical problems.

Starting consistency is another matter - could be cause by a number of things. How is the car not starting consistently? Is it not cranking? Not catching or having a hard time catching? How does it run otherwise? Idle quality, fuel economy changes?

Here is what I posted to my ongoing thread about this matter on supraforums..

I've changed all of the terminals on everything, but I am now very confused. The car would sometimes start once. I let it run for a few minutes, and then I turn it off. I try to start it again and I get nothing. I unhook the battery for a few mins, hook it back up, and sometimes it will start and sometimes it won't.

I have checked the two terminals on the starter solenoid with a volt meter and I did get good readings for both.

I am just lost in this whole thing. I'm just confused why it would start sometimes and then it'll be dead without changing anything! It's not the battery. I just had it charged and checked at autozone. I just don't know why it will start sometimes and then the next second it wont. This sucks.


Anyways, when I turn the key and it doesn't start, I hear a faint click, and that's it. When it does start, it start instantly, like nothing is wrong with it. What do you think?

[fishexpo101]

Could be the starter relay, starter solenoid, ignition switch issue, or a cooked battery. Sounds like you already covered the battery, battery terminals, and power to the starter. The battery could still be bad - batteries can test OK, but still be too weak. In your case, since it starts right up when it wants to - I'd double check the connections to the battery terminals (make sure the posts attached to the battery don't spin or more - make sure there is zero corrosion on the posts and battery leads), and check the connection to the solenoid on the starter. They may be tight, but if any corrosion gets in there - any high current draw may experience intermittent contact.

The click you hear inside the cabin is the starter relay - if you have a multimeter and some test leads (need to energize the relay to check operation) - you can test that out. Ignition switch is a little more involved - but if it either always starts just fine when you turn the key or cause the relay to click when it doesn't start - i.e., there are no times where turning the key produces nothing - then I would not suspect the relay.

Starter solenoid is the most likely culprit. You can have the starter checked out - but it sounds like an intermittent issue (heat soak, intermittent electrical supply, bad contacts inside - brushes). Low probably will be ground loops (doesn't sound like a ground loop issue as the starter is bolted to the transaxle) - I'd double check that it gets a pretty decent ground (measure the voltage between the starter body and the negative battery terminal - should be zero volts). Also a low probability is the ECM being at fault - not really known to be an issue on the 8th gen Corolla - but a bad ECM (wiring or hardware/firmware) could cause a start/no start condition.

If you can - hook the multimeter to the battery while your cranking the engine. Note how much the voltage drops as the starter cranks. Try it when it doesn't start - just clicks, does the voltage drop the same amount, a little bit, or doesn't change at all. No change means the either the ignition switch or relay are the problems. If it drops a little bit, could be a bad starter solenoid, if it drops alot - could be a burned up starter that is on its last legs. Of course, there are many other things that would cause the above symptoms and resulting voltage drops - but need to start somewhere.