Vacuum electrovalve
Moderator
Joined: Oct 2014
Posts: 4,336
From: North Central Indiana
A new experience gained.
I've jacked up front.
1. Did not start the engine, grab the wheel and turning one was making the opposite one turn into an opposite direction -> front differential locked. The shaft from transfer case remains steady.
2. Started the engine. Went throughly from 2Hi to 4 Hi and 4 Lo. In all the positions the behavior was as in pt. no 1.
3. To disengage the front differential I've stopped the engine[1]. and pulled the vacuum hose off the T-connector. The front differential got disengaged and wheels could turn freely.
The conclusion here is that the indicators on the transfer panel not going to indicate whether the front differential is in right or wrong position.
[1] It is not easy to pull the vacuum hose off the connector while vacuum is on. These plastic T-connectors are prone to breaking, I've already had that pleasure of making one of them. I made it from brass.
P.S. I left the car jacked, as I am expecting the electrovalve arrival today. Gonna put it on line and test if it works properly. That makes a tempting possibility to check the SRS front sensors...
EDIT:
I took my chance.
Passenger's side SRS sensor ok, around 1k. Same resistance can be read on the driver's side plug (A+C). Driver's side SRS sensor - A+B zero resistance, which is good. C+D fluctuates around 4-10k, should be around zero = busted. As You said, not easy to find these...
I've jacked up front.
1. Did not start the engine, grab the wheel and turning one was making the opposite one turn into an opposite direction -> front differential locked. The shaft from transfer case remains steady.
2. Started the engine. Went throughly from 2Hi to 4 Hi and 4 Lo. In all the positions the behavior was as in pt. no 1.
3. To disengage the front differential I've stopped the engine[1]. and pulled the vacuum hose off the T-connector. The front differential got disengaged and wheels could turn freely.
The conclusion here is that the indicators on the transfer panel not going to indicate whether the front differential is in right or wrong position.
[1] It is not easy to pull the vacuum hose off the connector while vacuum is on. These plastic T-connectors are prone to breaking, I've already had that pleasure of making one of them. I made it from brass.
P.S. I left the car jacked, as I am expecting the electrovalve arrival today. Gonna put it on line and test if it works properly. That makes a tempting possibility to check the SRS front sensors...
EDIT:
I took my chance.
Passenger's side SRS sensor ok, around 1k. Same resistance can be read on the driver's side plug (A+C). Driver's side SRS sensor - A+B zero resistance, which is good. C+D fluctuates around 4-10k, should be around zero = busted. As You said, not easy to find these...
Last edited by LesMyer; Aug 8, 2018 at 08:57 AM.
BF Guru
Joined: Dec 2016
Posts: 5,603
From: Moscow, ID
...
P.S. I left the car jacked, as I am expecting the electrovalve arrival today. Gonna put it on line and test if it works properly. That makes a tempting possibility to check the SRS front sensors...
EDIT:
I took my chance.
Passenger's side SRS sensor ok, around 1k. Same resistance can be read on the driver's side plug (A+C). Driver's side SRS sensor - A+B zero resistance, which is good. C+D fluctuates around 4-10k, should be around zero = busted. As You said, not easy to find these...
P.S. I left the car jacked, as I am expecting the electrovalve arrival today. Gonna put it on line and test if it works properly. That makes a tempting possibility to check the SRS front sensors...
EDIT:
I took my chance.
Passenger's side SRS sensor ok, around 1k. Same resistance can be read on the driver's side plug (A+C). Driver's side SRS sensor - A+B zero resistance, which is good. C+D fluctuates around 4-10k, should be around zero = busted. As You said, not easy to find these...
BF Guru
Joined: Dec 2016
Posts: 5,603
From: Moscow, ID
A new experience gained.
I've jacked up front.
1. Did not start the engine, grab the wheel and turning one was making the opposite one turn into an opposite direction -> front differential locked. The shaft from transfer case remains steady.
2. Started the engine. Went throughly from 2Hi to 4 Hi and 4 Lo. In all the positions the behavior was as in pt. no 1.
3. To disengage the front differential I've stopped the engine[1]. and pulled the vacuum hose off the T-connector. The front differential got disengaged and wheels could turn freely.
The conclusion here is that the indicators on the transfer panel not going to indicate whether the front differential is in right or wrong position.
[1] It is not easy to pull the vacuum hose off the connector while vacuum is on. These plastic T-connectors are prone to breaking, I've already had that pleasure of making one of them. I made it from brass.
P.S. I left the car jacked, as I am expecting the electrovalve arrival today. Gonna put it on line and test if it works properly. That makes a tempting possibility to check the SRS front sensors...
EDIT:
I took my chance.
Passenger's side SRS sensor ok, around 1k. Same resistance can be read on the driver's side plug (A+C). Driver's side SRS sensor - A+B zero resistance, which is good. C+D fluctuates around 4-10k, should be around zero = busted. As You said, not easy to find these...
I've jacked up front.
1. Did not start the engine, grab the wheel and turning one was making the opposite one turn into an opposite direction -> front differential locked. The shaft from transfer case remains steady.
2. Started the engine. Went throughly from 2Hi to 4 Hi and 4 Lo. In all the positions the behavior was as in pt. no 1.
3. To disengage the front differential I've stopped the engine[1]. and pulled the vacuum hose off the T-connector. The front differential got disengaged and wheels could turn freely.
The conclusion here is that the indicators on the transfer panel not going to indicate whether the front differential is in right or wrong position.
[1] It is not easy to pull the vacuum hose off the connector while vacuum is on. These plastic T-connectors are prone to breaking, I've already had that pleasure of making one of them. I made it from brass.
P.S. I left the car jacked, as I am expecting the electrovalve arrival today. Gonna put it on line and test if it works properly. That makes a tempting possibility to check the SRS front sensors...
EDIT:
I took my chance.
Passenger's side SRS sensor ok, around 1k. Same resistance can be read on the driver's side plug (A+C). Driver's side SRS sensor - A+B zero resistance, which is good. C+D fluctuates around 4-10k, should be around zero = busted. As You said, not easy to find these...
Thread Starter
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Senior Member
Joined: Nov 2017
Posts: 746
From: Poland
Never mind - I see you already posted that you have a 4-button system. Seems pretty strange that the hose is one-piece at that point. Please know that the front axle switch has to be installed so it vents the vacuum when it is shut off. Get it backwards and it will trap vacuum and front axle will stay engaged.
Exactly as You say - the front differential remains engaged while there is a vacuum. And vacuum won't go off too fast if the vacuum hoses are a new ones - there is a one-way valve in between plenum and the vacuum accumulator
The control panel will not indicate the switching problem if a front diff is permanently engaged.
I was expecting it to blink in 2WD as the diff did not disengage - it has a feedback sensor there for a reason, right?
I'd call it a bug
I've already cut the hose and installed the electrovalve. All works as expected.
Christine, Less - thank You for paying attention to my issue.
Thread Starter
|
Senior Member
Joined: Nov 2017
Posts: 746
From: Poland
If you cannot find a sensor in a wrecking yard, this might be a source: https://store.partshighway.com/new-o...l#.W2sDLNUzrIW
With my 2" body lift and 30" tires I feel safe enough amongst the other vehicles. In case of an impact I'll probably be high off the ground enough.
I gave a call to the person who sold me the engine asking for the sensor, and maybe I'll get a used one.As for the SRS line - it looks as a simple parallel connected sensors with a termination load of 1kOhm. It is a pretty common for an old fire detecting systems (new ones use the digital protocols and pulling). The SRS computer provides a power to the input line, and detects three cases.
1) Current does not flow or flows significantly lower than expected for 1kOhm load - means the wiring is damaged somewhere, so the air bag indicator goes on. State: FAULT.
2) A current value is around the expected value for the 1kOhm load - the system is in a normal state of operation. State: STANDBY.
3) One of the sensors gets shorted on impact, so the load and current surges. State: ALARM (air bag deploy).
I haven't look inside the sensor, but I expect it to be a passive transmitter of some kind. I could override the driver's sensor leaving the feedback from a passenger one. That would make at least half of the system work
BF Guru
Joined: Dec 2016
Posts: 5,603
From: Moscow, ID
No way, not for that cash amount :P
With my 2" body lift and 30" tires I feel safe enough amongst the other vehicles. In case of an impact I'll probably be high off the ground enough. I gave a call to the person who sold me the engine asking for the sensor, and maybe I'll get a used one.
As for the SRS line - it looks as a simple parallel connected sensors with a termination load of 1kOhm. It is a pretty common for an old fire detecting systems (new ones use the digital protocols and pulling). The SRS computer provides a power to the input line, and detects three cases.
1) Current does not flow or flows significantly lower than expected for 1kOhm load - means the wiring is damaged somewhere, so the air bag indicator goes on. State: FAULT.
2) A current value is around the expected value for the 1kOhm load - the system is in a normal state of operation. State: STANDBY.
3) One of the sensors gets shorted on impact, so the load and current surges. State: ALARM (air bag deploy).
I haven't look inside the sensor, but I expect it to be a passive transmitter of some kind. I could override the driver's sensor leaving the feedback from a passenger one. That would make at least half of the system work
With my 2" body lift and 30" tires I feel safe enough amongst the other vehicles. In case of an impact I'll probably be high off the ground enough.
I gave a call to the person who sold me the engine asking for the sensor, and maybe I'll get a used one.As for the SRS line - it looks as a simple parallel connected sensors with a termination load of 1kOhm. It is a pretty common for an old fire detecting systems (new ones use the digital protocols and pulling). The SRS computer provides a power to the input line, and detects three cases.
1) Current does not flow or flows significantly lower than expected for 1kOhm load - means the wiring is damaged somewhere, so the air bag indicator goes on. State: FAULT.
2) A current value is around the expected value for the 1kOhm load - the system is in a normal state of operation. State: STANDBY.
3) One of the sensors gets shorted on impact, so the load and current surges. State: ALARM (air bag deploy).
I haven't look inside the sensor, but I expect it to be a passive transmitter of some kind. I could override the driver's sensor leaving the feedback from a passenger one. That would make at least half of the system work
BTW, I was thinking of tearing apart my old sensor to see what the fault was. I suspect a bad connection to a circuit board for the external connector. I'm guessing this as I was able to move the pin a bit and got the sensor to work/not-work in a controlled manner by doing that.
Thread Starter
|
Senior Member
Joined: Nov 2017
Posts: 746
From: Poland
BTW, I was thinking of tearing apart my old sensor to see what the fault was. I suspect a bad connection to a circuit board for the external connector. I'm guessing this as I was able to move the pin a bit and got the sensor to work/not-work in a controlled manner by doing that.
P.S. To those who take it seriously - do not try this at home.
Moderator
Joined: Oct 2014
Posts: 4,336
From: North Central Indiana
Indeed Les. It was strange to me so I made the topic to ask more experienced than me.
Exactly as You say - the front differential remains engaged while there is a vacuum. And vacuum won't go off too fast if the vacuum hoses are a new ones - there is a one-way valve in between plenum and the vacuum accumulator
The control panel will not indicate the switching problem if a front diff is permanently engaged.
I was expecting it to blink in 2WD as the diff did not disengage - it has a feedback sensor there for a reason, right?
I'd call it a bug
I've already cut the hose and installed the electrovalve. All works as expected.
Christine, Less - thank You for paying attention to my issue.
Exactly as You say - the front differential remains engaged while there is a vacuum. And vacuum won't go off too fast if the vacuum hoses are a new ones - there is a one-way valve in between plenum and the vacuum accumulator
The control panel will not indicate the switching problem if a front diff is permanently engaged.
I was expecting it to blink in 2WD as the diff did not disengage - it has a feedback sensor there for a reason, right?
I'd call it a bug
I've already cut the hose and installed the electrovalve. All works as expected.
Christine, Less - thank You for paying attention to my issue.
Last edited by LesMyer; Aug 8, 2018 at 01:34 PM.
Thread Starter
|
Senior Member
Joined: Nov 2017
Posts: 746
From: Poland
Mine did stop flashing in 2WD. Still I do have an input sensor on a front axle too. I've seen it while the engine was taken out. It comes on my mind, that maybe we had a different software version and Yours from 2001 had the bug fixed, while mine 2000 wasn't.
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2nd Generation S-series (1995-2005) Tech
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