Menu toggle

Help | FREQUENCY MODULATOR CONTROL UNIT

thesmithsUK

thesmithsUK

PCGB Member
Member
Hi all,

The speedometer and rear spoiler on my 91MY 964 C4 suddenly stopped working today. (The rear spoiler light says on.)

My guess is that the Frequency Modulator control unit on the relay board may need replacing. Not cheap.

Or could it be one of the speed sensors? Also, not cheap!

Any pointers appreciated...
 
I understand that 'On the 1991 model, the signal comes in from the ABS unit as fed from the LF wheel sensor. It goes to R52, the Frequency Control Unit and also to R24 if you have a Carrera 4, then to the speedometer. The purpose of the FCU is to produce a square wave output using a device such as an ITT UAF 2115. The output of this integrated circuit is used to clean up the pulses from the ABS sensor'. Question remains: fault with the control unit or the speed sensor?
 
You must log in or register to reply here.

Posts made and opinions expressed are those of the individual forum members

Use of the Forum is subject to the Terms and Conditions

Disclaimer

The opinions expressed on this site are not necessarily those of the Club, who shall have no liability in respect of them or the accuracy of the content. The Club assumes no responsibility for any effects arising from errors or omissions.

Porsche Club Great Britain gives no warranties, guarantees or assurances and makes no representations or recommendations regarding any goods or services advertised on this site. It is the responsibility of visitors to satisfy themselves that goods and/or services supplied by any advertiser are bona fide and in no instance can the Porsche Club Great Britain be held responsible.

When responding to advertisements please ensure that you satisfy yourself of any applicable call charges on numbers not prefixed by usual "landline" STD Codes. Information can be obtained from the operator or the white pages. Before giving out ANY information regarding cars, or any other items for sale, please satisfy yourself that any potential purchaser is bona fide.

Directors of the Board of Porsche Club GB, Club Office Staff, Register Secretaries and Regional Organisers are often requested by Club members to provide information on matters connected with their cars and other matters referred to in the Club Rules. Such information, advice and assistance provided by such persons is given in good faith and is based on the personal experience and knowledge of the individual concerned.

Neither Porsche Club GB, nor any of the aforementioned, shall be under any liability in respect of any such information, advice or assistance given to members. Members are advised to consult qualified specialists for information, advice and assistance on matters connected with their cars at all times.

Porsche
Lockton
Pirelli
Officially approved
Oracle Finance
WEX Esso
Collecting Cars
Archant Dialogue
Back
Top