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AdamZ

New Member

• Aug 6, 2014

• #1

Hi All,

I have an RRC 4.2 LSE 1993. The speedo doesnt work, so I have decided to check what component could be wrong.

I have checked that the transducer gets 12V when ignition is on (unclipped the wire and checked the green-white cable according to the electric diagram), then removed the Transducer and the spiral cable and tested both. It works also, however the speedo instrument doesnt work.

see the test here:
20140807 RRC speedometer test - YouTube

Any experience whether the cable from the Speedo/ECU could get cracked somewhere?

do you where the return signal cable (red-black) goes exactly from the transducer so I could check the link at the end??

many thanks in advance

A

 

Last edited: Aug 14, 2014

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AdamZ

New Member

• Aug 6, 2014

• #2

121- speed transducer
184- speed buffer
186 - electronic speedo

So looks like either te speed buffer or the speed itslef wrong..

Speedbuffer located at left side footwell.
Any idea how i could test the relay once removed?

Thanks

A

 

Last edited: Aug 6, 2014

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AdamZ

New Member

• Aug 7, 2014

• #3

Some updates.

Speedbuffer (5 terminal relay-ish thingy) seems to be wrong as it sends no signal onwards (on terminal 87, 87a) to speedo when terminal 85,86 energised (ignition on). I have tested this with a voltmeter and 12V from the battery.

The speed buffer socket gets 12V from the transducer (pic).

 

ifloochies

Well-Known Member

• Aug 7, 2014

• #4

At least you seem to know what you're doing...
At this rate you'll certainly have it going again in no time.

 

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AdamZ

New Member

• Aug 7, 2014

• #5

ifloochies said:

At least you seem to know what you're doing...
At this rate you'll certainly have it going again in no time.

Click to expand...

I hope!
I had no idea on electrics before this, just reading the workshop manuals and ETMs I could find on the web and trying figuring out the electric wiring diagrams


Has anyone tested the speed buffer relay? how it should work when it gets the 12 V on terminal 85/86? or maybe its not a usual 5 terminal relay...

thanks





A

 

Last edited: Aug 7, 2014

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stopover

Active Member

• Aug 7, 2014

• #6

I have a speed buffer relay you can have for free if it will help? pm me your address and I will pop it in the post, only take it if you need it - also have speed transducer and speedo head unit if things get tricky but will need a little mula for those.

 

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AdamZ

New Member

• Aug 7, 2014

• #7

stopover said:

I have a speed buffer relay you can have for free if it will help? pm me your address and I will pop it in the post, only take it if you need it - also have speed transducer and speedo head unit if things get tricky but will need a little mula for those.

Click to expand...

thanks for the offer very nice of you.

I have ordered a speed buffer last nite for few quids, and I hope that will solve the issue (though it will take 7 days to deliver, so I will update you within a week)

if that doesnt help, I may consider your speedo head unit (if its from a 1992-1994 RRC) for a fair price, so please keep that reserved for me )

thanks
A

 

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AdamZ

New Member

• Aug 14, 2014

• #8

Got my replacement Speedo Buffer relay (PRC8882) this morning. Fitted right away.

I have made the volt measuring well on the components and wiring, as my speedo works now, indeed the speedbuffer relay was faulty )

 

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Last edited: Aug 14, 2014

zen

Well-Known Member

Events Planner

• Aug 16, 2014

• #9

if you can solder , then resolder the buffer components..cos its so simple proberble fault is likley to be dry joint in buffer..(only a few resistors and a transistor)

once done swap it out..if works keep as spare..