Aux water / turbo fan issue.....

[jes*b]

As this all started after the engine got a mud bath in salisbury I think it relevant to post up here. Also not getting many takers on the other channel ( also posted up in electrical )

Issue is both aux water pump and turbo cooling fan are coming on and running continuously but not when they should ) ie when engine gets very hot) I swapped relay behind left hand rear light cluster but not changed anything. Could it be a faulty switch ? Are they both connected to the same sensor / switch? Cheers to lloydy for a wiring diagram but not made much sense of that dark art as yet. Anyone had a similar issue?

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[garyd]

Jes,
from the wiring info I worked out when doing my AGG (GTi) conversion I believe that the sensor for the fan/pump is mounted in the hose flange on the side of the cylinder head. If memory serves correctly, the JX has only a single sensor (the GTi has two) with a brown wire with a red trace plus a brown earth. This will be F95 in the wiring diagram which provides an earth return for the fan.

Since the power to the fan comes direct from the P1 post in the heater plug relay box, via the 50A fuse and the connection from 2/30 on J52, the fan will run anytime the F95 thermo switch is closed. This will normally be due to high water temperature but might be the source of your fault. Are the terminal wires shorted together? Has the sensor failed closed? Check with continuity meter?

Relay J151 provides the few seconds of earth connection (while the heater plugs operate at start-up) to allow the fan to spin up and prevent it from seizing up through lack of use. The wires under the relay (in the diagram) on 6/85 & 8/87 are earthed through the wires from 6/85 of J52. On my 83 series diagrams there is an earth link shown from 6/85 of J52. It also shows an earth link direct from 6/85 of the J151 relay.

Relay 151 is triggered to close in these circumstances by the ignition switch in the heater plug position. This provides power via the 'b' line and E4 to terminal 7/50 of the relay J52. This closes J52 but the link to terminal 4/50 of J151 also energises this coil and closes the contacts.

So, the basic system is essentially very simple. Continuous power plus a high temperature thermo switch bring the pump in when required. All the complication is to give it a regular burst of use to prevent seizure. (A bit like diff-locks?). J151 will be the relay behind the nearside rear wheel arch.

I have no direct information about the fan but, I believe that it is wired in parallel with the pump so that they operate together. You check for & trace any additional wires on the F95 terminal, for instance?

Hope this helps

Garyd

[jes*b]

Garyd, really useful write up. I will run through this with the wiring diagram at hand and with head in engine bay. As both the fan and pump are cutting in ( at low engine temp) and not cutting out I am assuming the fault is common to both so sensor will be my stating point.

Electrics not my strong point so will be useful to finally decode a diagram with your notes.

All useful research for when I go etdi

[jes*b]

Garyd, really useful write up. I will run through this with the wiring diagram at hand and with head in engine bay. As both the fan and pump are cutting in ( at low engine temp) and not cutting out I am assuming the fault is common to both so sensor will be my stating point.

Electrics not my strong point so will be useful to finally decode a diagram with your notes.

All useful research for when I go etdi

[Simon Baxter]

What usually happens is some bell top changes the switch for a sender.
Take off the wire to the switch, earth it and the fan and pump should run.
If it does, switch fault.
If it doesn't, wiring or relay [or fuse]
There's the usual "some clown got some crimping pliers for Christmas" repairs to overcome too,
When I've had problems that weren't the obvious it has been terminals that have gone all green and corroded in the relay socket behind the left rear light.

[max and caddy]

When the key is turned to the start 50 posisitions the aux water pump runs....not sure if the fan does too however, this stops the pum seizing up...I don't thing the greater plugs have any influence on it...50 denotes start in the din wiring numbers so maybe the pin 7/50 is also a start signal,into the glow relay to tell it something....

[jes*b]

Continuity test revealed thermo switch had failed closed - i am guessing it is original , looks like it has seen better days - rubber o ring was also letting by. i reckon due to heavy load/ heat build up in a couple of recovery scenarios whist at salisbury the switch was asked to do its job and came up wanting. New switch from Baxter, and relay from rob and all sorted.