TACHOMETER & SPEEDOMETER

1989 Mercedes Benz 300se

Tiny

bryan321

February, 26, 2009 AT 4:10 PM

Electrical problem
1989 Mercedes Benz 300se 6 cyl Two Wheel Drive Automatic 185000 miles

About a year ago my tachometer quit working after the engine was revved while driving and the transmission shifted abruptly.

A few months ago my speedometer quit working too. I have the web driven Mercedes Service manual from MB but I have been unable to find any information in the manual on how to trouble shoot or fix either problem.

FOUND 909 RELATED QUESTIONS

7 Answers

Tiny

rasmataz

February, 26, 2009 AT 4:17 PM

If it was me I'll start with the speedometer impulse transmitter on left rear of transmission.

Tiny

bryan321

February, 26, 2009 AT 4:21 PM

What about the Tach? I saw on a parts website that there are speed sensors on the front wheels. Are these for the ABS system? Not the speedometer.

Tiny

rasmataz

February, 26, 2009 AT 4:35 PM

Does it have a vehicle speed sensor I've looked couldn't find one-check that if it has one.

The ABS rpm sensor is at the front and back of the vehicle and also it has its on computer

Tiny

bryan321

February, 26, 2009 AT 4:50 PM

Just got off the phone w MB dealership. He could not find the speedometer impulse transmitter as a stand alone part. He mentioned a transmission harness. He also mentioned that the tachometer runs off of an engine componant, cam, crank, alternator. Do you have any ideas what runs the tachometer?

Tiny

rasmataz

February, 26, 2009 AT 4:59 PM

The CPS gives the computer the piston postions and engine speed, CMH synchronizes the injectors and what stroke its in

Tiny

bryan321

February, 26, 2009 AT 5:06 PM

What is CPS & CHM?

Tiny

rasmataz

February, 26, 2009 AT 5:16 PM

CPS --Crankshaft Position Sensor

CMH--Camshaft Position Sensor

Please login or register to post a reply.

Instrument Cluster Replacement GMC Yukon
Coolant Temperature Sender Replacement
Door Panel Removal & Speaker Replacement
Open Hood Video