RPM needle

WBREYNO

MEMBER
1998 SATURN SL1
4 CYL
FWD
AUTOMATIC
133 MILES

I have a 98 Saturn SL1. Here recently when I am driving, the RPM meter acts normal until the needle "ticks" all the way around until it hits the red and it can move any further, it then continues to "tick" in the same spot but this doesnt affect my engine at all. The needle wont go back to normal until I turn my car off and restart it. My check engine light hasnt come on to tell me if something is wrong. Do you have any idea what may be going on? Thanks in Advance

3 Replies

SATURNTECH9

MECHANIC
30,870 POSTS

Let's start by seeing if you have any code's even though your check engine light hasn't come on.I haven't come across a car that does what you describe.

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Saturday, December 4th, 2010 AT 2:08 AM

WBREYNO

MEMBER
2 POSTS

I went by advance autoparts and there isnt any codes that come up.

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Saturday, December 4th, 2010 AT 7:18 AM

SATURNTECH9

MECHANIC
30,870 POSTS

TACHOMETER
The tachometer is directly controlled by the powertrain control module (PCM) using a Pulse Width Modulated (PWM ) signal based on the signal received from the Crankshaft Position (CKP ) sensor. The PWM signal to the cluster is passed through an RC filter and sent to the tachometer driver integrated circuit (IC). The high-to-low edge of the PWM signal triggers the IC to provide a well defined pulse of current to the coil of the tachometer. The engine completes one revolution for every six pulses received from the PCM. The PCM monitors circuit 121 for an open, short to ground or short to voltage and will set DTC P1693 if certain parameters are met.
The first thing I would look for is pinched or chaffed wire's in the engine compartment that's where I would start.

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Sunday, December 5th, 2010 AT 10:49 PM