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Flashing coolant telltale?

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So yesterday I pulled out my Esprit from storage. After I was able to break into it (view "locked out!" thread for info) started the car up, let warm up for a few mins, and took for short drive. In total had the car running for about 30-45 mins with no issues at all. Parked the car on the driveway and went back to work. Came home 4-5 hours later and started the car to move inside the garage. Soon as I started it the coolant telltale was flashing. I first thought it was that the coolant level was low, so I topped off the header tank which did need a bit, but not much. Restarted the car and it was still flashing. Checked the book and it says that a flashing telltale means that the car is overheating. That, however, isn't the case. It was completely cold when I started and moved into the garage. Anyone have any ideas? Possibly temperature sending unit? Where is it located? Thanks

Steve

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dont know if th v8 header tank is the same as the 4 post, but i had the same problem on my se. the sender units in the bottom of the header tank become faulty. quick fix tap the sender with a long screwdriver. fixed mine. failing that remove ond clean out tank

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This has been discussed many times, it's a common problem. There's a tube with a float in it in your header tank, it gets gunked up and the float sticks hence the false reading. Take the tube out, give it a good clean and replace, jobs a peach :blush:

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Ok, I will give that a whirl, but doesn't this have to do with coolant level? That would be consistant with a coolant light steadily on. Mine is flashing, which the book tells me is an overheating light. That is not the case as it is doing it on a cold start. Thanks.

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in the tube is just 'a floater' -as you say , for level sending...

But do you have the ECM calibration with the additional 'high oil/high engine-temp' feeler in the sump ?! Think this could mean some irritation or interferences together with the ordinary temp.-sensors on top of the front left side of the engine block -..if there is an fault in the wiring or so..

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As you say, on the V8 a flashing coolant light means overheating (a steady light is for low coolant). Do the radiator cooling fans kick in immediately? If not are you getting a CEL (it monitors the coolant sensor and trips the light if any of the sanity checks fail, e.g. open circuit, closed circuit).

Otherwise I would suggest looking at the oil temperature sensor which is screwed into the bottom of the sump and a lot easier to get to than the coolant sensor!

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No check engine light and no, the fans are not triggering as they shouldn't because the coolant is cold. I would highly doubt it was the oil temp sensor as I broke that piece off 2 years ago and drove for an entire year before putting in the new one last summer. During that time I never had an issue. I guess I could unplug that sensor, though, and see if that turns the light off. Thanks.

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Update, still dealing with this problem. Haven't driven the car all summer because of it. Replaced header tank sensor after waiting for a month and a half to get it. Started car and light was off, yay!! (battery had been disconnected for a month in between). Had car running for an hour no issues. Turned off and came back 2 hrs later to leave with car and the damn light is flashing again!!!! :( No codes, just light flashing. I'm really getting annoyed at this. Is there not a temp sensor somewhere on the engine that controls this light?? Temp gauge seems to work fine, but light always flashing. I'm thinking there is a seperate sensor for the light. Does anyone know whether this is the case? Thanks

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water temp. for reference ECM ->twin wire sensor slightly LH under the plenum (just on the front end of the engine -timing belt side)

water temp. for Instrument gauge cluster ->single wire sensor, just next to the other -same location

water level. for Instrument tell tale ->floater sensor in the water reservour

oil temp. for ECM -> on some cars (production period/ market lelatet), on the drain plug in the lower sump level

with other words , I would imagine that Oil & Water temp. together influence the ECM in decissions made -to signal an 'overheat' situation (so as that the 'twin wire water sensor' & the sensor in the oil drain-plug in the sump)

And the single wire sensor (also on top of the block, under the plenum) is only for the instrument needle in the gauge. But have to verify this later on in the wiring shemes if you need further infurmations..

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Hi Gunter, thanks for the info. Finally going to have a chance to look at this situation tomorrow. Summer is winding down here and finally might have a chance to drive the car!! If the oil sensor is an issue I will just unplug it. I drove for a year without it when I broke it and never threw a code or a light. Will also take a look at the sensors. Will keep you posted.

Steve

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Update. Checked sensors. Temp gauge appears to be working fine. Disconnected light sensor and light keeps flashing. When I jump the two wires and ground fan comes on, but light still always flashing. If i jump to wires from header tank and ground light goes on solid. Gonna drive the car some today with light flashing and see if it throws any code.

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all I can say is -the description on 'flashing' comnpared wit 'steady' is in the workshop book , or in the other post above mine.

Maybe the wiring plan can clear who is driving the lines to the tell-tale light. As far as I understand it -one means 'low' level and is simply activated by an level sensor ..and one means 'overheat issues' and is activated by the ECM. So you should measure the wirings and follow the line towards the ECM pin-contacts ..just to be sure :unsure:

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Problem resolved!! It was the damn oil temp sensor in the drain plug!!!! Unplugged the sensor and light went out. Got a new one on order from JAE. Looking forward to driving now without annoying flashing light for a change.

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Glad that you resolved the problem - I wonder if that is a US specific thing. The oil temperature sensor was added to the engine later in life, but I´ve not heard of the coolant light flashing if there was a problem there.

Hope that you can get some enjoyment from the car before she is sold.

Cheers,

Mike S

Edited by mike_sekinger

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Thanks Mike, yes it was a weird situation. Happy to say I was able to put over 250 miles on the car over the weekend. May not want to sell it now that it is working so well, haha.....

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