green george Posted May 1, 2016 Share Posted May 1, 2016 The good news is that the mechanical pressure gauge is reading a healthy 65 psi at idle and the engine sounds sweet, which leads to me to think that the switch may be faulty. The switch (Think Auto 20 psi switch part no.: EWS/1C @ £18.88) is nearly new. Is there a way of testing it? Or, is it simply a matter of purchasing another switch? I do have a multi tester, but would need to know which scale to use etc.... I have been working on the car today prepping the chassis for some POR/15 which has necessitated applying to the chassis POR15 Marine Clean and then the POR15 Metal Prep each washed off with copious amounts of water. Thinking the water may have shorted the switch (which is attached to the (offside engine mount), I have sprayed the spade terminals with WD40, but the light is still on.Any ideas? Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted May 1, 2016 Member Share Posted May 1, 2016 Do you think it is fully bright? With the ignition on and the engine not running confirm that the light is now on. Ignition off. Disconnect at the sender end the lead that runs from the sender to the gauge. Ignition on and engine not running: what happens to the light?After that we can move to the multimeter...JonathanEdited for added safety. Link to comment Share on other sites More sharing options...
green george Posted May 1, 2016 Author Share Posted May 1, 2016 Do you think it is fully bright? No, it appears to brighten when the engine starts and then stays at that level of increased brightness.With the ignition on and the engine not running:(I assume the light is now on.) Disconnect at the sender end the lead that runs from the sender to the gauge. What happens to the light? The light goes out and if I reconnect the lead it comes back on.Not, sure if this has any relevance, but I use a red LED as the low pressure warning light. Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted May 1, 2016 Member Share Posted May 1, 2016 ... I use a red LED as the low pressure warning light. But with exactly the same set-up it was working correctly before the wash and brush up?Jonathan Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted May 1, 2016 Member Share Posted May 1, 2016 That switch type has two terminals, but I don't know if the body is connected to one side of the switch and can make the circuit to earth.One terminal should be connected to the gauge. What is connected to the other... what colour of wire and can you see where it goes?Jonathan Link to comment Share on other sites More sharing options...
green george Posted May 1, 2016 Author Share Posted May 1, 2016 Hi Jonathan, yes it has been working fine, having been installed by Chris at 7 Workshop, last year. I only mentioned that as I beleive that using LED's for direction indicators and lights sometimes generates its own problems. Link to comment Share on other sites More sharing options...
green george Posted May 1, 2016 Author Share Posted May 1, 2016 Hi Jonathan,You are right. One terminal leads to the light (not the gauge which is mechanical) and the other terminal leads to an earth on the block. The earth appears to be good i.e does not move.George Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted May 1, 2016 Member Share Posted May 1, 2016 Assuming that your cleaning and spraying has removed the possibility of a short to earth between the two terminals...Remove the sender from the block and repeat the sequence in Post #2 and check that the behaviour is the same. And after that I can see two diagnostic strategies Test how the resistance of the disconnected sender varies as you change the pressure through 20psi... could be done in another engine or with a pump (eg a foot pump for tyres) if you can get a seal. I don't know the nominal resistance values but it should be either obviously conducting or not. Try another sender. (Just as you suspected.)Jonathan Link to comment Share on other sites More sharing options...
green george Posted May 19, 2016 Author Share Posted May 19, 2016 Hi Jonathan,Still waiting for a new sender from Think Auto as they are on back order. I thought I would take a look so this afternoon I removed the sender, to find there was very little to see, so blew in the hole and put it back.... In answer to your question about whether the light was fully bright, I noticed that when I started the car having replaced the sender the light was initially much brighter than with the ignition on. It then started flickering.George Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted May 24, 2016 Member Share Posted May 24, 2016 Looking forward to seeing what happens with the new sender... Jonathan Link to comment Share on other sites More sharing options...
green george Posted May 29, 2016 Author Share Posted May 29, 2016 Changed the low oil pressure sensor for a new one and the problem is cured. Upon starting the engine the low oil pressure light extinguishes immediately. Very relieved it wasn't electrical gremlins. Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted May 29, 2016 Member Share Posted May 29, 2016 Well done.Jonathan Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now