98 Civic Speedo jumps/check engine light

The other day I was driving home, cruising at a constant speed when
suddenly my speedo dropped down to zero and the check engine light came
on. After that, the speedo jumped all over the place, past 100 mph,
back to zero, totally random, and the transmission started shifting
weird, so I figured it wasn't just my speedometer... I unplugged the
connector for the Vehicle Speed Sensor, and now the transmission is
pretty much back to normal, but of course, I still have my check engine
light, and the speedo stays at zero.
Today, I installed a new speed sensor, and I get the exact same problem
- clunky transmission, crazy speedo... So now I think it must be
something else, like wiring or grounds. I've also noticed that
occasionally I my dash lights and dome light seem to "throb", but
that's been happening since before the speedo problem. I've seem other
posts online where others had the same problem, but noone ever said
what it was. Should I be looking at my alternator, wires, grounds, or
is it possible I got a brand new broken speed sensor?
I have no problem checking all that stuff, but hoped somebody would
read this that had the same issue and could save me some
troubleshooting time.

Thanks,
Randy

wrote:
> The other day I was driving home, cruising at a constant speed when
> suddenly my speedo dropped down to zero and the check engine light came
> on. After that, the speedo jumped all over the place, past 100 mph,
> back to zero, totally random, and the transmission started shifting
> weird, so I figured it wasn't just my speedometer... I unplugged the
> connector for the Vehicle Speed Sensor, and now the transmission is
> pretty much back to normal, but of course, I still have my check engine
> light, and the speedo stays at zero.
> Today, I installed a new speed sensor, and I get the exact same problem
> - clunky transmission, crazy speedo... So now I think it must be
> something else, like wiring or grounds. I've also noticed that
> occasionally I my dash lights and dome light seem to "throb", but
> that's been happening since before the speedo problem. I've seem other
> posts online where others had the same problem, but noone ever said
> what it was. Should I be looking at my alternator, wires, grounds, or
> is it possible I got a brand new broken speed sensor?
> I have no problem checking all that stuff, but hoped somebody would
> read this that had the same issue and could save me some
> troubleshooting time.
>
> Thanks,
> Randy
>
for ~$60, you can go to sears and get a code reader. your car is obdcII
compliant. or you can have the codes read for free by some auto parts
stores. once you have the code, you can fix the problem.

Jim,

I just got the codes read: Speed sensor & both oxygen sensors. That
doesn't really help *me* at all. Like I said, I already tried replacing
the speed sensor, and the oxygen sensors wouldn't seem to have anything
to do with the symptoms I described.

-Randy

jim beam wrote:
> wrote:
> > The other day I was driving home, cruising at a constant speed when
[snip]
> >
> > Thanks,
> > Randy
> >
> for ~$60, you can go to sears and get a code reader. your car is obdcII
> compliant. or you can have the codes read for free by some auto parts
> stores. once you have the code, you can fix the problem.

wrote:
> Jim,
>
> I just got the codes read: Speed sensor & both oxygen sensors. That
> doesn't really help *me* at all. Like I said, I already tried replacing
> the speed sensor, and the oxygen sensors wouldn't seem to have anything
> to do with the symptoms I described.

so what are the codes? i mean the readout numbers, not what you've been
told they are.

>
> -Randy
>
> jim beam wrote:
>
wrote:
>>
>>>The other day I was driving home, cruising at a constant speed when
>
> [snip]
>
>>>Thanks,
>>>Randy
>>>
>>
>>for ~$60, you can go to sears and get a code reader. your car is obdcII
>>compliant. or you can have the codes read for free by some auto parts
>>stores. once you have the code, you can fix the problem.
>
>

wrote:
>
> The other day I was driving home, cruising at a constant speed when
> suddenly my speedo dropped down to zero and the check engine light came
> on. After that, the speedo jumped all over the place, past 100 mph,
> back to zero, totally random, and the transmission started shifting
> weird, so I figured it wasn't just my speedometer... I unplugged the
> connector for the Vehicle Speed Sensor, and now the transmission is
> pretty much back to normal, but of course, I still have my check engine
> light, and the speedo stays at zero.
> Today, I installed a new speed sensor, and I get the exact same problem
> - clunky transmission, crazy speedo... So now I think it must be
> something else, like wiring or grounds. I've also noticed that
> occasionally I my dash lights and dome light seem to "throb", but
> that's been happening since before the speedo problem. I've seem other
> posts online where others had the same problem, but noone ever said
> what it was. Should I be looking at my alternator, wires, grounds, or
> is it possible I got a brand new broken speed sensor?
> I have no problem checking all that stuff, but hoped somebody would
> read this that had the same issue and could save me some
> troubleshooting time.
>
> Thanks,
> Randy
---------------------------------------------

Even if you aren't covered by the GREAT IGNITION SWITCH RECALL, it might
be your problem.

Was it changed? Here's the link for the ACCORD version of the recall:
http://www.tegger.com/hondafaq/tsb/accord/x02-031e.pdf

Google will find you lots more symptoms.

'Curly'

wrote:
> The other day I was driving home, cruising at a constant speed when
> suddenly my speedo dropped down to zero and the check engine light came
> on. After that, the speedo jumped all over the place, past 100 mph,
> back to zero, totally random, and the transmission started shifting
> weird, so I figured it wasn't just my speedometer... I unplugged the
> connector for the Vehicle Speed Sensor, and now the transmission is
> pretty much back to normal, but of course, I still have my check engine
> light, and the speedo stays at zero.
> Today, I installed a new speed sensor, and I get the exact same problem
> - clunky transmission, crazy speedo... So now I think it must be
> something else, like wiring or grounds. I've also noticed that
> occasionally I my dash lights and dome light seem to "throb", but
> that's been happening since before the speedo problem. I've seem other
> posts online where others had the same problem, but noone ever said
> what it was. Should I be looking at my alternator, wires, grounds, or
> is it possible I got a brand new broken speed sensor?
> I have no problem checking all that stuff, but hoped somebody would
> read this that had the same issue and could save me some
> troubleshooting time.

my 1998 hatch did the same thing. fixed under warranty. the wiring
harness with the VSS got loose and was rubbing against a bracket under
the intake manifold, supposedly.

i wonder if theres a TSB about it?

wrote:
> Jim,
>
> I just got the codes read: Speed sensor & both oxygen sensors. That
> doesn't really help *me* at all. Like I said, I already tried replacing
> the speed sensor, and the oxygen sensors wouldn't seem to have anything
> to do with the symptoms I described.

its gotta be the wiring loom under the intake manifold. there is no
other answer.

id put money down that all those wires are bundled together.

jim beam wrote:
> wrote:
>> Jim,
>>
>> I just got the codes read: Speed sensor & both oxygen sensors. That
>> doesn't really help *me* at all. Like I said, I already tried replacing
>> the speed sensor, and the oxygen sensors wouldn't seem to have anything
>> to do with the symptoms I described.
>
> so what are the codes? i mean the readout numbers, not what you've been
> told they are.

itll be interesting to know, but... i remember we had a poster here with
the same problem. and i had it too. wasnt there a TSB on the engine
wiring harness under the intake manifold?

FWIW I had the exact same symptoms with my '96 Civic.

It also turned out to be the wiring harness shorting out somewhere
under the intake manifold.

Thanks for all the great input! SoCalMike, I found a TSB that sorta
fits the symptoms:
http://downloads.hondatech.info/Auto...n/x99-029e.pdf
I just followed the TSB and tore into it, but couldn't find any damaged
wires. I guess I'll have to keep looking, especially after the reply
below.
Thanks again!


wrote:
> FWIW I had the exact same symptoms with my '96 Civic.
>
> It also turned out to be the wiring harness shorting out somewhere
> under the intake manifold.