Temp gauge

[southernscouse]

Fitted the slaughterhouse kit April 22 when running a DG been ok until I laid up the van to put in a DJ

[southernscouse]

So today noticed that if I let the red light flash for a count of 14 then started up the light would go out if I started up straight away the red light would continue flashing even after driving some distance
This is still without the relay and my count of 14 was what my dash did when working ok
Will this help to diagnose what’s happening

[AngeloEvs]

From your description, the LED pulses continually even with the module 43 (42) removed when the ignition is first switched on and continues to pulse. That sounds very much what happens when one of the following occurs:-

1. the regulator voltage falls below 9.25v

2. the voltage regulator connection at the gauge is intermittent

3. The Temp gauge Earth connection (centre nut of the gauge) is making poor contact with the dash 0v earth which terminates at the earth crown cluster next to the fuse box.

4. the internal Temp gauge circuit develops a continual LED pulsing fault condition due to a capacitor failure.

The best way to confirm if any of the above is the problem is to test the dash or remove the gauge and test it separately. You could also try a different temperature gauge if you have one spare or try someone else’s dash in your van if you know someone with a T25 that is compatible with yours (pre 1987 or post 1986 model) Pity you are not local as I could carry out a full bench test on the dash and the gauge for you.

[southernscouse]

Well today swapped the temp gauge fo a spare now everything is working as it should and on switching on the ignition the light flashes for a count of 8 so I am now. In the position of everything ok again let’s just see how long it lasts thanks for all the help on here cheers Tom

[AngeloEvs]

Most likely the capacitor has failed in the gauge circuit. Unfortunately, electrolytic capacitors do fail and have a limited operational life. After 40 years there will be quite a few temp gauges suffering ‘permanent flashing’ but the good news is that the capacitor can be replaced. Happy to do a write up for the wiki describing removal and replacement of the capacitor.

[southernscouse]

Hi Angelo if you need a gauge to fix the capacitor you could take mine this would be good for the wiki and would also confirm that my cap is the problem and if you return it to me I would replace my spare let me know the costs involved be more than happy to pay Cheers Tom

[AngeloEvs]

Hi Angelo if you need a gauge to fix the capacitor you could take mine this would be good for the wiki and would also confirm that my cap is the problem and if you return it to me I would replace my spare let me know the costs involved be more than happy to pay Cheers Tom

Sent you a pm.

[southernscouse]

Got your pm thanks I don’t think I am the only person with this problem

[southernscouse]

Well today drove down to southsea for the VW meet on the common the light behaved as normal but the needle on the gauge was reading a bit high just past the led parked up spent about 5 hours there
Set off and the needle moved straight to the high side and the light stayed flashing
Being a gipsy had to remove the rear seats and carpet to check the level in the main water tank all ok so drove home with light flashing and gauge right over to hot

What’s the first thing I should do after the exorcist

[AngeloEvs]

Did the gauge indicate overheating as soon as the engine was started?  

Sounds like a short circuit across the gauge if the gauge needle moves to the overheating position at start up (the LED will flash when the needle moves to the overheating position - that is normal).  You removed module 43 and were still getting problems, I bench tested your gauge and it was ok, you fitted another gauge and still have problems which  only leaves the wiring to the coolant temperature sender or the sender itself but I have never heard of a sender going short circuit - usually they go open circuit).  

 

[southernscouse]

Just read this reply so went out removed relay43 started up still the same flashing light and gauge over to hot now that I know the gauge you tested is ok my next move is to swap them over so that is one thing out of the equation.

[AngeloEvs]

I would disconnect the wiring to the sender, start up and see if that cures the problem. While you have it disconnected measure the resistance across the sender and across the two wires. If the resistance is very low then there is a problem with the wiring.

[southernscouse]

Right today. Removed relay 43 gauge right over and light flashing
Removed level sensor wire same as above
Removed temp sensor wires as above
Wired jumped temp sensor wires as above
Removed dash panel plugged and unplugged 14 wire connector as above

[AngeloEvs]

If the temp gauge is moving to the overheat position even with the wires to the sender disconnected then there a short circuit or very low resistance across the gauge. The only other component that can cause that fault is if module 43 goes short circuit but you are getting the same fault with it removed. Does the DJ have the plastic thermostat housing with a temp sender and a thermal switch?

[southernscouse]

It’s a 1986 van the dj has the plastic thermostat housing with 2 sensors not sure what you mean by thermostat switch can’t see one in the Haynes thanks