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  #31  
Old 02-13-2020, 06:52 PM
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Quote:
Originally Posted by andrewwynn View Post
Symptoms match BST opened. See if the car will start with a jump start. Actually you can self-jump-start with a long enough jumper cable: jump from the positive battery terminal to the B+ under the hood. If it starts the BST is open. You can get a repair kit but a lot of people will get a full cable from a junk yard


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What is the 'BST'? This is really frustrating. How the hell can this be? A battery dies, you replace the battery and then the car won't start when it was running perfectly well before then? This is a RIDICULOUS problem with this vehicle!
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  #32  
Old 02-13-2020, 07:24 PM
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Originally Posted by jagarundi View Post
What is the 'BST'? This is really frustrating. How the hell can this be? A battery dies, you replace the battery and then the car won't start when it was running perfectly well before then? This is a RIDICULOUS problem with this vehicle!
BST = Battery Safety Terminal. It's on the positive battery clamp on the thicker wire coming from battery to engine bay. It's part of the restraint system cutting power to engine bay after collision. If you have normal voltage on the engine bay jump start point BST is OK.
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  #33  
Old 02-13-2020, 07:33 PM
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My theory is that manipulating the battery pos terminal opened up the contact in the BST. It's a longshot but it perfectly matches the symptoms


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  #34  
Old 02-13-2020, 07:33 PM
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Originally Posted by Clavurion View Post
If you have normal voltage on the engine bay jump start point BST is OK.
Maybe.... but not always.

BSTs can "soft-fail" where they have enough of a connection for the low current draw (like from a multi-meter) to still allow full voltage to be apparent but when you draw a large current, the voltage loss at the BST become significant and the car won't start. The BST has in effect become a high-resistance joint.

I doubt this is the issue in this case though, as with a high-resistance BST the engine would likely try to turn over but not. Also the electrical load of simply turning on the ignition would pull the apparent terminal voltage down a lot too.

Which reminds me - we've seen a few high-resistance joints at the B+ terminal on the front bulkhead too - I guess this is another possibility? Not sure it matches the symptoms though - sounds more like an EWS issue.
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  #35  
Old 02-13-2020, 08:12 PM
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Maybe.... but not always.

BSTs can "soft-fail" where they have enough of a connection for the low current draw (like from a multi-meter) to still allow full voltage to be apparent but when you draw a large current, the voltage loss at the BST become significant and the car won't start. The BST has in effect become a high-resistance joint.

I doubt this is the issue in this case though, as with a high-resistance BST the engine would likely try to turn over but not. Also the electrical load of simply turning on the ignition would pull the apparent terminal voltage down a lot too.
That is true. For this purpose you should also check the engine bay voltage while starting. But like you said if BST was on partial contact the starter solenoid would likely click even if there was not enough power to rotate engine.
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  #36  
Old 02-14-2020, 12:35 AM
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I doubt this is the issue in this case though, as with a high-resistance BST the engine would likely try to turn over but not. Also the electrical load of simply turning on the ignition would pull the apparent terminal voltage down a lot too.



Which reminds me - we've seen a few high-resistance joints at the B+ terminal on the front bulkhead too - I guess this is another possibility? Not sure it matches the symptoms though - sounds more like an EWS issue.

Only the starter and alternator are fed through the BST.

Either B+ loose or BST open with cause the symptoms. (among other possibilities) but it's an easy test: jumper from battery pos to B+ under hood. If it starts, likely BST open.

Make sure B+ is tight. When I replaced alternator recently I just removed the bolt from B+ to disconnect battery.
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