Serious and Sarcastic Question

[RussJeep1]

Why did FCA put not one, but two hood open sensors on the rig, but only one ESS battery?

Granted, there may be a very good reason I am missing for the fault tolerance of redundancy here under the hood, but shouldn't that redundancy be saved for things either more likely to fail, or if they do, render the rig in serious trouble?

Was the double hood latch in case a visual impaired person (who shoudn't be driving in the first place) was driving the rig, didn't realize the hood was open, and one of the two hood open detectors failed, and they needed to be warned of this dangerous condition?

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[Chocolate Thunder]

Ever driven a vehicle with and unlatched hood and reached highway speed before realizing it? I have (‘95 Dodge Ram). The results are not safe, pretty, or cheap. A dead ESS battery is an inconvenience for certain, but not likely to cause damage or a crash.

 

[Kent5]

As I understand it, they are not redundant. The two sensors serve different purposes and are connected to different systems.

 

[RockyMtnHigh]

I believe one is for the ESS, and the other is an alarm in the case that the hood is opened without the key fob in range (I.E., when someone wants to steal your battery)

 

[Jebiruph]

As I understand it, they are not redundant. The two sensors serve different purposes and are connected to different systems.

I agree with this. Different systems may not be able to share the same sensor. IIRC my Focus has 3 sensors on the brake pedal.

 

[RussJeep1]

Ever driven a vehicle with and unlatched hood and reached highway speed before realizing it? I have (‘95 Dodge Ram). The results are not safe, pretty, or cheap. A dead ESS battery is an inconvenience for certain, but not likely to cause damage or a crash.

I hear you. Honestly, I've never driven a vehicle, at least that I recall, that didn't have the hood latch attach itself (as designed for safety) to the hood to prevent that you describe, even if the hood wasn't properly closed.

 

[RussJeep1]

As I understand it, they are not redundant. The two sensors serve different purposes and are connected to different systems.

I hear this, but would it not beg the question as to why these multiple systems couldn't share the same switch?

I know...sometimes different systems operate via different electronic mechanisms of different current types (e.g. AC/DC, and not the heavy metal band), voltage and amperage. But that's where relays address this.

I'd put my money on a well designed relay, tested for millions of opening and closings of circuits before failure over a manual devise like a hood open button or (granted I don't know its exact design) 3 different brake sensors.

Also, FWIW, I fully appreciate that actuaries are figuring out the likelihood of failure and the litigious implications of same in vehicle systems when it comes to design, and where to put the redundancies.

 

[digitalbliss]

I hear this, but would it not beg the question as to why these multiple systems couldn't share the same switch?

I know...sometimes different systems operate via different electronic mechanisms of different current types (e.g. AC/DC, and not the heavy metal band), voltage and amperage. But that's where relays address this.

I'd put my money on a well designed relay, tested for millions of opening and closings of circuits before failure over a manual devise like a hood open button or (granted I don't know its exact design) 3 different brake sensors.

Also, FWIW, I fully appreciate that actuaries are figuring out the likelihood of failure and the litigious implications of same in vehicle systems when it comes to design, and where to put the redundancies.

You would prefer one switch to control multiple things? Why?

 

[WXman]

One switch for the alarm, one for the ESS system. Not all JLs have both systems, and on the ones that do you wouldn't want the alarm system failing if the switch for the ESS went bad. Having two switches here is good.

 

[RussJeep1]

You would prefer one switch to control multiple things? Why?

My answer would depend on the quality of the switch, the systems it controls, the cost of the switch, its likelihood of failure, the costs associated with its failues, and its MTBF (mean time between failure), to name just a few factors.

If one switch isn't backing up the other here then additional switches don't give any fault tolerance, just les "fit hitting the shan" when one of those switches fails.

Don't get me wrong, I'm not anti multiple switches when it's indicated as such, just curious why THIS was the thing FCA sought to distribute the damage on by assigning tasks to multiple switches, when the ESS battery should have been more robust.

My question crosses legitimate interest with a hit of seeming irrationality at FCA's fault tolerance decisions, particular related to the ESS battery--but again, like I said from post #1, I plead ignorance.

 

[RussJeep1]

One switch for the alarm, one for the ESS system. Not all JLs have both systems, and on the ones that do you wouldn't want the alarm system failing if the switch for the ESS went bad. Having two switches here is good.

I appreciate how redundancy on fully loaded or uniquely configured rigs sometimes proves the best design, especially as a matter of cost savings, building, etc.

But are there some JLs that don't have both these switches?

 

[Bubba33]

Ya I don't believe there is any hood alarm. There is a safety switch so it can't be remote started if the hood is open.

 

[G13]

Ya I don't believe there is any hood alarm. There is a safety switch so it can't be remote started if the hood is open.

I was at a dealer to test drive Rubicon. The sales guy went inside to grab a key, and he remote started to see if he had the correct key. It started another one, and the Rubicon we were going to drive. He came out with only the Rubicon key, and he tried to stop the wrong one by pressing start button. It didn’t work, so he popped and the engine stopped.

 

[Bubba33]

I was at a dealer to test drive Rubicon. The sales guy went inside to grab a key, and he remote started to see if he had the correct key. It started another one, and the Rubicon we were going to drive. He came out with only the Rubicon key, and he tried to stop the wrong one by pressing start button. It didn’t work, so he popped and the engine stopped.

Are you saying he opened the hood and it shut off. It's a safety switch remote start wont work with low fuel , check engine light on or doors or hood open.

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