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Fans do not turn on


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I have a 1995 Esprit S4s with revised harness.

So this is a new one I have not seen in 11 years of ownership.  My radiator fans will not come on.  The three radiator fan fuses are good and the fuse that goes to the relay is good and the relay works as I can turn it on and off with espritmon. With the car running, using espritmon, i press the fan on button and the relay clicks and the fans do nothing.  I turn the A/C on and the fans do nothing. 

I dont see anything interesting on the wiring diagram after the fan control relay. The only thing I have had off the car is the earthing strap that runs between the driver and passenger seats as I had the seats out of the car.

Where would you guys start to look at this point?

Thanks

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Verify that the connectors to the fan relay are still tight and not backed out of their plastic base. Current draw and loose connections can result in heat, which softens the retainers.

 

Also, verify that your fan relays have not been switched around.  Some are single contact, some are dual contact, and DON"T sway the two types.

Atwell Haines

'88 Esprit

Succasunna, NJ USA

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Posted (edited)

There is only one fan relay.  its revised harness.  there is nothing in the trunk.  So the fans switch on at 87C through one full cooling down cycle then switch off and never come on again.  The car will heat all the way up to redline and the fans wont move.  If i turn the car off and let it cool all the way down.  The exact same thing happens.  car will heat up, fans will kick on and cool the car back down then the fans will turn off and wont come on again.  Additionally, the vacuum solenoid valve, EBPV is getting hot but the other two solenoids are cool to the touch.  not sure if any of this is related?

Edited by wohlmeyer
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Espritmon is also showing a random code 26 QDM.  And the car is running rich.  The QDM code 26 is not persistent.  I can also manually turn the fans on with espritmon all the way until the first cooling cycle then espritmon won’t activate the fans anymore.

2 hours ago, wohlmeyer said:

There is only one fan relay.  its revised harness.  there is nothing in the trunk.  So the fans switch on at 87C through one full cooling down cycle then switch off and never come on again.  The car will heat all the way up to redline and the fans wont move.  If i turn the car off and let it cool all the way down.  The exact same thing happens.  car will heat up, fans will kick on and cool the car back down then the fans will turn off and wont come on again.  Additionally, the vacuum solenoid valve, EBPV is getting hot but the other two solenoids are cool to the touch.  not sure if any of this is related?

 

Espritmon is also showing a random code 26 QDM.  And the car is running rich.  The QDM code 26 is not persistent.  I can also manually turn the fans on with espritmon all the way until the first cooling cycle then espritmon won’t activate the fans anymore.

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I have had intermittent relays before.  Any chance the relay is acting up.  I had a fuel pump relay that would cut out over the occasional bump on a Porsche and I think a window relay on the Esprit that sometimes did not work.  When I took the Esprit relay apart I could clearly see heat related damage.  I wonder if it would be worth changing the relay just to confirm.  Just swap the ECU with a known good one 🙂   yeah right, good luck with that.  I think there is a place that will go through the ECU and repair but I cant think of where I saw it. 

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William,

Trying to look at the simple things first,

 

You might have one or more bad connections to the ECU socket. Either the 'input' side (that transmits the signal from the temp sensor under the intake) or the 'output' side that sends the voltage to the relay. Seen that regards the speedo signals at the ECU, on a friend's S4s.

 

Speaking of that sensor, maybe that is what is 'heat soaking' and is preventing the fans from turning on.

 

Tell the CAR WIZARD he disturbed the wiring when he replaced your head gasket... 🥴😇 LOL

Can't wait for the video....

 

PS:  What injectors are you running?  Improper injector impedance can set the code 26, and if the resistance is marginal, that code can come & go.

Ask JAE if they can recommend a place that can test/repair the GM ECUs, post back here if they know of one. I know that SOME owners just needed to re-solder components.

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Atwell Haines

'88 Esprit

Succasunna, NJ USA

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Before you attempt ECU brain surgery, have you checked all the simple things that have been suggested? I’m thinking you’d be pretty sick if it turns out to be something minor like a bad connection or relay. Not saying it is, but checking will cost you nothing, that’s all.

Margate Exotics.

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5 hours ago, Erikl said:

I have had intermittent relays before.  Any chance the relay is acting up.  I had a fuel pump relay that would cut out over the occasional bump on a Porsche and I think a window relay on the Esprit that sometimes did not work.  When I took the Esprit relay apart I could clearly see heat related damage.  I wonder if it would be worth changing the relay just to confirm.  Just swap the ECU with a known good one 🙂   yeah right, good luck with that.  I think there is a place that will go through the ECU and repair but I cant think of where I saw it. 

Thanks for your reply.  I have a box full of relays (11 years of ownership) that I have accumulated over the years.  The relay that controls the fans I have 2 brand new ones and 2 of the yellow colored original Lotus relays.  All 4 relays work just fine and for good measure I have tried all 4 in the slot.  The relay clicks on but the fans do nothing, sometimes...  Sometimes the fans will click on for at least 1 cooling cycle before they crap out and do not come on no matter what I do.  I can turn the relay on and off with espritmon and sometimes the fans will come on when I do this...sometimes they will not.  As far as ECU's go, i have replaced the ECU before.  It is not a big deal.  They are GM ECU's.  All you have to do is switch over the Chip and Mem-cal.

 

Bill

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5 hours ago, CarBuff said:

William,

Trying to look at the simple things first,

 

You might have one or more bad connections to the ECU socket. Either the 'input' side (that transmits the signal from the temp sensor under the intake) or the 'output' side that sends the voltage to the relay. Seen that regards the speedo signals at the ECU, on a friend's S4s.

 

Speaking of that sensor, maybe that is what is 'heat soaking' and is preventing the fans from turning on.

 

Tell the CAR WIZARD he disturbed the wiring when he replaced your head gasket... 🥴😇 LOL

Can't wait for the video....

 

PS:  What injectors are you running?  Improper injector impedance can set the code 26, and if the resistance is marginal, that code can come & go.

Ask JAE if they can recommend a place that can test/repair the GM ECUs, post back here if they know of one. I know that SOME owners just needed to re-solder components.

Thanks for the reply.  I have a place that sources ECU's.  I have replaced my ECU once before.  It is not hard, you just have to swap in the Chip and the Mem-cal. Blank ECU's are cheap.  They get expensive when you want one that is plug and play. I will check the connections going in and out of the ECU.  I know I have good sensors because I can watch them all function from espritmon.  They all have the correct voltage and I can watch that temperature sensor rise all the way to critical, ALL the while, espritmon is reporting that the ECU is commanding the fans to turn on and sometimes they will and sometimes they will not.  The car is also running rich and one of the solenoids (the one for the exhaust) gets hot, these are all the things that were happening the last time I replaced the ECU.  The car ran great after that.  not sure what I am going to do this time.  I might just take it to my tuner and let them fool with it.  My tuner sources the ECUs and has a TECH-1 on hand.  He is what you might call a Lotus Esprit Wizard.  The CAR WIZARD I have known for years.  He is very good at a lot of general things and is very good with electrical diagnosis, however, he does not have a TECH-1 and even if he diagnosis a bad ECU, he does not know how to source them like my other guy.

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4 hours ago, Chillidoggy said:

Before you attempt ECU brain surgery, have you checked all the simple things that have been suggested? I’m thinking you’d be pretty sick if it turns out to be something minor like a bad connection or relay. Not saying it is, but checking will cost you nothing, that’s all.

Weird thing is, espritmon and free scan are both showing all is well.  Ive tried multiple known good relays and there is no change. I think I have taken it as far as I can without a TECH-1.  It might be time to trailer it to my tuner for a professional look under the hood.

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So here is an update. I disconnected my temperature sensor at the manifold thinking it would make my fans come on immediately.  Nothing happened.  I checked for voltage at the relay and had 12 volts.  I started probing around with my voltmeter after the relay until I found the connector pictured below.  I shoved the ends of my volt meter prongs into the back of the connector and my fans came on.  I pulled the prongs out and the fans shut off.  I pulled on the connector wires and wiggled them a bit and the fans came on.  So i think I need a new cooling fan harness and this will solve my issues.

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188620906_1425664111123392_6952667242273046286_n.jpg

186503080_3958628344226522_8766909265799952792_n.jpg

185793413_280379707163822_4993290723235453052_n.jpg

185980357_251920876723103_1573589616913090690_n.jpg

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Where is that connector?

 

Would a thin zip-tie hold it together temporarily (and enable the fans)?

Atwell Haines

'88 Esprit

Succasunna, NJ USA

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2 hours ago, CarBuff said:

Where is that connector?

 

Would a thin zip-tie hold it together temporarily (and enable the fans)?

It’s in the frunk and a part of the cooling fans wiring harness.  It doesn’t need a zip tie, it’s partially melted together.

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7 hours ago, CarBuff said:

Where is that connector?

You'll find it tucked away under the front relay station not far from the three fan fuses.

Norfolk Mustard S4s #1 :)

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