VSS......and TCC?

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myc1972@netzero.net - 11 Dec 2005 04:24 GMT

Hello,
I have a 1986 Oldsmobile Delta88 3.8L V6.
This winter i started getting the "Service engine soon" light. I took
it to be fixed and they retrieved a TPS code. The sensor was replaced
and adjusted.

But now i am getting another "Service engine soon" light with a code
24, which is a
Vehicle Speed Sensor (VSS) code. The light comes on the first time i
run the car in the
morning, when the wheels are not moving (parked). And when i start
moving the service
engine soon light turns off. It does not come back for the rest of the
day.
The car also has a high idle.

The car starts to do a surge condition when i start to brake for a red
light.

Recently i had a leak from the power steering lines that run over the
transmission. Could
this have caused this problem? Maybe got on the VSS or TCC contacts.

Any of you guys ever have this problem?
What you think it might be?

I already spend much this winter.

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putt@webtv.net - 11 Dec 2005 13:07 GMT

>i am getting another "Service engine
> soon" light with a code 24, which is a
>Vehicle Speed Sensor (VSS) code.

24 is the Speed Sensor Circuit problem code. It's not just about the
VSS, it concerns the whole electrical speed sensor circuit. You had the
TPS replaced and now there is a throttle problem. Possibly the TPS is
adjusted correctly and/or the ISC throttle switch is Open. Do you know
if the code is stored as a Hard code or an Intermittent one? Prior to
the first problem, was the speedometer working correctly?

This electrical problem has little/nothing to do with the transmission
converter clutch(TCC).

Dave S(Texas)

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Steve Mackie - 11 Dec 2005 15:11 GMT

> But now i am getting another "Service engine soon" light with a code
> 24, which is a
[quoted text clipped - 4 lines]
> engine soon light turns off. It does not come back for the rest of the
> day.

I am reading through the diagnostic aids and it says "disregard code 24 that
sets when drive wheels are not turning." Do you have any other codes coming
up?

It also says "a faulty or misadjusted park/neutral switch can result in a
false code 24." I would start by diagnosing that.

Steve

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myc1972@netzero.net - 11 Dec 2005 16:02 GMT

The Code 24 gets stored in the computer, it does not get erased unless
i disconnect the
battery. Would that make it a Hard code? As far as i could tell the
speedometer has
been working correctly always.

When the car starts to surge when i apply the brakes there is no
Service engine soon light
that comes on.

I also read that if that code 24 is set when the drive wheels are not
moving to disregard it.
but i am still getting the surging and high idle, so there is a problem
somewhere.

Thank you for replying so fast guys, i really appreciate it, i need all
the help i can get.

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putt@webtv.net - 12 Dec 2005 15:44 GMT

>i am still getting the surging and high
> idle, so there is a problem somewhere.

Yes, and I'm saying it is in the TPS/ISC units. Take the vehicle back
to the garage that installed the TPS and relate the problem. I believe
the ISC wasn't serviced correctly when the TPS was installed. The ISC
is in Open position when it should be in Closed position.

Dave S(Texas)

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myc1972@netzero.net - 13 Dec 2005 04:11 GMT

what is the ISC?

Thanks!

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Sharon K.Cooke - 13 Dec 2005 14:08 GMT

> what is the ISC?
>
> Thanks!

ISC = Idle Speed Controller
It adjusts for a steady idle speed by compensating for engine load via input
from the TPS (Throttle Position Sensor). The ISC can get carboned-up internally;
some have cleaned them, but replacement is recommended.

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putt@webtv.net - 13 Dec 2005 20:05 GMT

>what is the ISC?

>Thanks!

Thanks....is that your name??

Anyway, the ISC is short for Idle Speed Control. It is a small
electro-mechanical unit that lives near the TB. The ECM senses
variations in voltage from the TPS and uses those signal the ISC. If
the ISC wasn't properly set after the new TPS was installed, the problem
you describe is the result. BTW: disconnecting the power to the ECM is
not a good way to clear the codes. Doing that clears all the driving
history that has been built-up....this is the RAM in the computer.
Losing the RAM makes the ECM revert to using the ROM. The ROM is the
inbedded memory from when every system/sensor on the vehicle was
brand-new. The RAM is the compensation (program) for the ROM. The
vehicle won't run very well while it's using only the ROM. Eventually a
RAM will be rebuilt with driving, but it takes time. Most good scan
tools have a feature to 'clear' the codes, without also 'clearing' the
RAM.

Dave S(Texas)

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