Service LTPWS Light

[Nick]

Question about the Service LTPWS light in my '94 ZR-1. Replaced the wheels and omitted the sensors. Anyone have any idea how many miles of driving it takes before the Service LTPWS light comes on? Mine just came on last night, after over 400 miles of driving without the sensors. :confused:
Thx.

[Peaven]

I've heard that there is sometimes a bit of delay before the light comes on when you remove the sensors....I can't speak from firsthand experience though, since I just went ahead and yanked the bulbs out of the DIC 1st.:cheers:

[zrss]

It's been a couple years but I seem to recall it took a little over 500 miles for the one in my '94 to come on.

[GOLDCYLON]

On the late Zs its hit or miss. But unless you put the sensors back in or take the blub out of the DIC the light will remain on. THis is not the case for 90-91 Zs

[jonszr1]

i took the front ones ourt of one of my 90s and it still comes on. on thje yellow one I took the rears out and it didnt come on . anyone know why that is?

[GOLDCYLON]

i took the front ones ourt of one of my 90s and it still comes on. on thje yellow one I took the rears out and it didnt come on . anyone know why that is?

Nope I heard all four need to come out on the 90-91s for the light to stay out. What year was the yellow one was the blub already removed from the DIC?

[jonszr1]

the yellow car is a 91 and the light worked till the day i took the rear sensors out . go figure

[WB9MCW]

here is my weirdness

mine comes on every start

after 1/8 mike it goes out

it has been doing it for years now

i figure someday when it doesn't go off -- i'll fix her then

[jonszr1]

i did the hoaky fix, a small sq of electric tape

[tomtom72]

Bryan, your issue may be a sticky or lazy fariday battery. If the thing don't slide easily then it doesn't generate enough electricity to transmit. Our sensors are just like those hookey flashlights...ya know the ones you gotta shake before they light up?

I have one, a right front, that acts out once in awhile. It sets the Service LTPWS light & if I drive fast enough for a while it goes out.:mrgreen:

:cheers:
Tom

[WB9MCW]

TT why does it light up every start up?? I only go abt 15mph for the one mile out of my private road so speed in not an issue since it turns the light off in abt 1/16 to 1/8 mi down the private drive.

[QB93Z]

Bryan, your issue may be a sticky or lazy fariday battery. If the thing don't slide easily then it doesn't generate enough electricity to transmit. Our sensors are just like those hookey flashlights...ya know the ones you gotta shake before they light up?

I have one, a right front, that acts out once in awhile. It sets the Service LTPWS light & if I drive fast enough for a while it goes out.:mrgreen:

:cheers:
Tom

Tom, Thanks for the great explanation. For a long time I have wondered about how the transmitters worked.
Jim

[WB9MCW]

maybe mine just keeps tripping the LTPWS circuit and that is why my light keeps coming on at startup

[GOLDCYLON]

maybe mine just keeps tripping the LTPWS circuit and that is why my light keeps coming on at startup

Thats possible I wonder if the LTPWS reader is the culprit vs one of the sensors?

[zr1don]

I have a 1990 that the LTPW lite would come on after 1/4 mi or so of driving. It has no wheel sensors. I removed the DIC bulb.

[tomtom72]

Over at the Net Reg site in the How to section......if I remember right....:o
is a write up on how the sensors and the receiver works. If I remember right the sensor has an inductive battery and a capacitor to store juice, upon start up when the ECM goes thru its' testing routien it "listens" for all the sensors to report in. If the capacitor is failing or if the "battery" don't move freely the sensor may not have enough to "report in".

Like with mine it seems after bit of driving the Ser LTPWS light comes on, then after I drive for a while the light goes out buy itself or if I stop & shut down and re-start the light stays out maybe for awhile & comes back on or it stays out. The write up said that most of the false DTC's from the sensors were due to the battery not moving freely to make enough juice for the capacitor to store.....It has been a while since I read the write up so I proly don't have all the facts straight! :o

:mrgreen:

[WB9MCW]

Yes I read that whole description/write up too. But my problem is the inverse. Every time I fire the Z up the service light in on after a 1/16 mile poof out she goes like clockwork--so I figure all is OK by just have to wonder why does the light come on every start up?

My guess is that for some reason the ecm is triggered somehow to do this--not sure why this would be the case--just plain wierdness--good olde Murphy is hangin around my ecm or somewhere...

I was really wondering if anyone else has ever had such a strange cycle/rut as my Z is having.:icon_scra

[tomtom72]

Bryan, two things come to mind.

The capacitor is not holding a charge long enough to report it on the next start up, like sitting overnight or longer.

The Fariday battery is weak.

I vote for the first guess because the light goes out quickly after start up & car movement. Unlike my issue which I suspect is the battery not moving freely enough to charge my capacitor quickly enough and that the capacitor maybe marginal at best.

It is my impression that the LTPWS along with everything else on the DIC goes thru a test directly after motor start up...or at least within the first few minutes after the motor is running. If there is no juice/or not enough juice to transmitt then the Service LTPWS light sets.

:cheers:
Tom

[WB9MCW]

That my dear TT is the "beacon of reality" I was looking for---an answer that makes sense--the cap is not holding my charge--yep I bet that is it--it must be real bad since it will come on even after a very short time of sitting---This weekend I will try multiple starts in a row and see if it comes on every time!!!
I suspect it will which means my cap must be really shot--well at least enough signal makes it to turn off the light once I get rolling---

[sledutah]

Nope I heard all four need to come out on the 90-91s for the light to stay out. What year was the yellow one was the blub already removed from the DIC?

I took all 4 sensors out of my '91. After about 400 miles the light came on and stays on. :icon_scra

[Nick]

I took all 4 sensors out of my '91. After about 400 miles the light came on and stays on. :icon_scra
I solved the "problem" last night in no more than 30 minutes and with only a few tools. Didn't even need a hammer. :mrgreen: Pulled the bulb and all is well. :thumbsup: