Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing 1996 +4 VDO Temperature Gauge

Hi all

Does anyone know how and where the temperature gauge gets it's feed from, on a 1996 +4 with VDO gauges, Rover T16 engine and MEMS ECU?

There is a redundant wire (connected to the gauge) near the thermostat and a blanked space for a sender. There is also a temperature sender on the thermostat which feeds the ECU.

There is no wiring diagram available for this age of +4, as far as I know.

I think the feed might, possibly, come from the ECU.

Any information would be gratefully recieved.

Thanks

David Stuart

I'm not sure if this helps

I'm extrapolating from my 4/4 and guessing a bit, but I believe it would be a separate temperature sender, probably in the side of the engine block. I think the VDO instruments of that era were analogue jobs like the Smiths setup on my 1986 4/4. On my car there's a temperature sensor integral with the thermostat which feeds the ECU, but the ECU doesn't provide a signal out, it's just used for internal purposes like switching the fan.

This theory appears to be backed up by this: VDO Instruments Wiring Guide

But if as you say there's a wire leading nowhere from the back of the gauge and a blanked-off sensor location, it does indeed imply an ECU signal. But that would imply a wire from the gauge to the ECU. Here's the MEMS ECU pinout spec and you can see there's no send pin to a temp gauge

The Haynes manual for the Rover car says :- Removal
4 The coolant temperature sensors contain
an element, the resistance of which alters
according to coolant temperature. The units
control the operation of the temperature
gauge, and are also used by the fuel and
ignition system control units to determine
engine temperature. Depending on the engine
management system fitted, either a single
sensor performs both functions, or a separate
sensor is used for each.
5 On 4-cylinder engines either a single
sensor, or two sensors are located on the
thermostat housing. On V6 engines a single
sensor is located in a coolant passage on top
of the engine, just below the distributor.
6 Partially drain the cooling system
(approximately 2.5 litres) as described in
Chapter 1.
7 Disconnect the wiring multiplug, then
unscrew the relevant sensor from its location

Thanks for your replies gents.

I have checked the pinout for MEMS1.9. There is no output for coolant temperature.

I have looked around the engine and don't see any sensors which look very likely candidates.

In the end, there will be a simple answer! I will continue to follow up any hunches.

Thanks again

David Stuart

Is the sender plumbed in to a coolant hose by any chance? Here's my car, which although completely different from yours might be a clue what to look for, the gauge sender sits in a little housing in the main coolant pipe from thermostat to radiator. In this pic you can see the thermostat with the temp sender for the ECU at the top of the pic, and the gauge sender is at the bottom.