Wiring question

[icb]

Having speedo problems - can anyone confirm that from speed sensor the wiring goes to ECU then to speedo. Chimaera 4.5 1997. Have the bible for colour codes. Thanks a lot.

[dannyboyo]

Mines just packed up too!! I know the speedo sensor feeds pin 6 on the ECU, but I think it splits off before that, and half feeds the ECU and half feeds the speedometer. Not 100% though!

I think to test the sensor, you need to unplug the ECU, get a multimeter, put one probe on ground, and the other on pin 6 of the connector. Then with the ignition on, rotate the wheels and the meter should bounce between 0v and 12v if the sensor is working. Not had a chance to try it myself yet though! Good luck and let me know how u get on

Edited to say, mines a late '95 4.0 Chimaera

>> Edited by dannyboyo on Saturday 8th March 06:40

[david beer]

Iam sure all TVRs are different but my 99 griff has has a black box for the speedo that just sits behind the dash. I tapped in there for the sat nav, unfortunately it doesnt pulse until 8mph so did something else.

[ribol]

Having speedo problems - can anyone confirm that from speed sensor the wiring goes to ECU then to speedo. Chimaera 4.5 1997. Have the bible for colour codes. Thanks a lot.

Have been trying to get a 100% answer to that one for months, nobody on here knows. I have an intermittent speedo problem and have been assured that the sensors either work or don't. That being the case it must be either the clock itself or a bad connection which is why I have been trying to find out exactly how the speedo side of things works. Please let me know if you get to find out.

Ivan

[shpub]

It is pretty well described in the bible 2. The problem is that you may or may not have an adapter box between the sensor and speedo input. Unless you are prepared to strip out the dash, it can be difficult to say with any certaintity which system you have and whether the speedo and ECU connections are simply tied together.

You will need to remove the dash to get to the speedo connections and you will need a scope and some way of driving the wheels at 10-15 mph and add to that the fact that your fault is intermittent and it is a swine to diagnose. The sensor will have an earth and power connection and the the power connection is connected to the ecuy/speedo. This is not a direct 12 volt connection as the sensor will change the current flowing through it to signal the pulses which is why you need a scope and not a multimeter as the meter can often screw up the operation.

Steve
www.tvrbooks.co.uk