Erratic Tachometer on '87 Pulsar

Thread view:

Enable EMail Alerts

Start New Thread

Thread rating:

T.C. Mann - 09 Feb 2008 01:20 GMT

I have an '87 Pulsar (E16i SOHC) Engine with 155,000 miles on it. For
the last couple of days the tachometer has been fluctuating
inconsistently with the true RPM of the engine. For example, I'll be
driving at 65 MPH with the tach reading around 3000 RPM (normal) and
then all of a sudden it will drop to a few hundred RPM or even zero
for a few seconds and then it will return to normal. Or sometimes,
when the car is first started it will read zero and then it will be
normal. The engine runs smooth and starts just fine so the problem
seems to be just with the tach. The other gauges are working fine.
Does anybody know where the tach gets its signal from or the location
of its connector under the hood? If someone knows of an online source
or could post the schematic for the tach circuit that would be great
too. Thanks.

Reply to this Message

still just me - 10 Feb 2008 02:26 GMT

>I have an '87 Pulsar (E16i SOHC) Engine with 155,000 miles on it. For
>the last couple of days the tachometer has been fluctuating
[quoted text clipped - 9 lines]
>or could post the schematic for the tach circuit that would be great
>too. Thanks.

Next time it happens, whack the dash hard above the tach and see if it
fixes it. If it does, it's likely the tach unit.

There's a voltage regulator on the back of the instrument cluster too.
I forget if it will cause erratic operation or if the gauges just die
when it goes bad.

Reply to this Message

Andrew Chaplin - 10 Feb 2008 04:02 GMT

>>I have an '87 Pulsar (E16i SOHC) Engine with 155,000 miles on it. For
>>the last couple of days the tachometer has been fluctuating
[quoted text clipped - 16 lines]
> I forget if it will cause erratic operation or if the gauges just die
> when it goes bad.

I have a similar problem with my '91 Pathfinder and it also affects my
speedometer, but it is very occasional and whacking the dash usually produces
a useful reading. I have checked the speedo on measured miles, and it reads
fairly consistently 5% low at highway speeds.

Signature

Andrew Chaplin
SIT MIHI GLADIUS SICUT SANCTO MARTINO
(If you're going to e-mail me, you'll have to get "yourfinger." out.)

Reply to this Message

T.C. Mann - 11 Feb 2008 23:44 GMT

> On Fri, 8 Feb 2008 17:20:06 -0800 (PST), "T.C. Mann"
>
[quoted text clipped - 19 lines]
> I forget if it will cause erratic operation or if the gauges just die
> when it goes bad.

I tried hitting the dash as you suggested but no change. If the
instrument cluster regulator that you're referring to fails, it
affects not only the tach, but the fuel, and temp gauges as well. In
my case, all the other gauges are working fine. Also, when the
regulator fail, it's usually done for and not intermittant.
Hopefully, this will help someone with a similar problem. T.C.

Reply to this Message