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Wiring issue - Engine temp sensors

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    Posted: July-14-2018 at 4:58pm
While trying to diagnose my recent surging issue with the new engine I've taken the upper intake back off to rule out any air/ vacuum leaks and noticed a wire that had inadvertently been hidden under the port side wiring harness. I had labeled all the wires as I disassembled the engine early last winter, one at a time so that I didn't get them confused so this one really has me perplexed.
This wire was labeled 'water pump temp sensor' and had a ring terminal on the end, looking like a factory job since it was wrapped in the factory loom. The problem was there was another wire coming from the starboard side that had been labeled 'water temp' already leading to the water pump. I remember that this was the last wire I had connected because it wasn't specifically labeled water pump so it was just a process of elimination.
There's another wire on the starboard side labeled 'water temp' that was only long enough to reach the temp switch that is installed in the intake just after the thermostat housing so naturally I would assume that this is where it had been previously installed. Of course the 3rd water temp sensor in the intake on the port side has a connector and is obviously proprietary to that sensor.   

I've traced the wires to find their color and consulted the wiring diagrams and this is where it gets confusing.   The wire that I had discovered under the harness is tan which according to the GT40 owners manual wiring diagram indicates should be the water temp sensor, presumably mounted on the water pump and lead to pin #8 on the main wiring harness. Tracing the wire color of the one previously on the water pump discovered it to be tan/ black which according to the GT40 service manual (SLOW circuit) should lead to the engine temp switch mounted on the starboard side intake manifold.
Pretty simple so far, right? Nope.   Because there was a wire already installed there as well, labeled "water temp sensor' coming from the starboard side wiring harness and was only long enough to reach that temp switch - strange since I was thinking the switch should only be part of the SLOW circuit. Tracing this wire, it's been spliced 3 times with various shades of green wire, but does lead back to a connector with a factory green wire that then goes to the wiring harness that leads to the helm.   Again consulting the GT40 owners manual, the green wire with the connector is stated to be part of the 'engine alarm circuit' and attaches to both the water temp switch and the oil pressure switch.   

So there is the problem - one manual says both switches are connected in tandem with a tan/ black wire as part of the SLOW circuit and the other says they are connected together with a green wire as part of the engine alarm circuit.   One way or another, I have an extra lead and no sensor, or switch, to connect it to ... unless one of those has two leads on it which is something that neither manual indicates.   

Since apparently the original wiring wasn't connected correctly when I bought the boat, I'm at a loss as to where these are supposed to go and the manual(s) seem to be telling me two different stories, any help deciphering which wire goes where and why I seem to have an extra lead would be appreciated.
Thanks,
JCCI
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Post Options Post Options   Thanks (0) Thanks(0)   Quote gt40KS Quote  Post ReplyReply Direct Link To This Post Posted: July-14-2018 at 5:10pm
Thought a few pics for orientation might help







I believe the temp switch and pump sensor are wired correctly now. I have the tan wire from the starboard side harness connected to the water pump sensor and the tan/ black wire connected to the intake water temp switch.   So where does the green wire go??



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Post Options Post Options   Thanks (0) Thanks(0)   Quote KENO Quote  Post ReplyReply Direct Link To This Post Posted: July-14-2018 at 9:30pm
I think the mysterious part is that if these were wired backwards you'd have an on-off temperature switch wired to your temperature gauge or the ECM

I think you should have 2 senders and 1 switch

Section 6-3 of the same manual has more info to confuse you also.

Have you started the engine with this wiring rearrangement that you just did?

The link below has some good Lewy 2001 info in the 8th post of the thread

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Post Options Post Options   Thanks (0) Thanks(0)   Quote KENO Quote  Post ReplyReply Direct Link To This Post Posted: July-14-2018 at 10:02pm
In this picture of somebody's multicolored engine (with a crooked decal) you can see the hole for one sensor or switch at the left front of the lower intake, a little behind the oil fill pipe.

Then right behind the thermostat housing there is a sensor or switch right there already installed in the picture (right in front of the blue masking tape)

And you have one on the water pump.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote gt40KS Quote  Post ReplyReply Direct Link To This Post Posted: July-14-2018 at 10:02pm
Mysterious is right Ken - I watched the temp gauge climb and level off countless times. I suppose you have to factor in that not only was the wiring wonky from the beginning, but I have to wonder if all the senders were even the correct ones. I replaced the water and air temp senders located in the intake on the starboard side when reassembling the engine but all the others were reused. I ordered the correct ones from NP yesterday just to be sure.


Still not exactly sure where the 'green' wire designation comes from (bottom diagram) but it is clear that they are connected to the same switches depicted in the other 'SLOW circuit' diagram (tan/ black wires). But with the two tan/ black wire leads connected to those two switches, where do I connect the ring terminal with the actual green wire? I'm going to trace the wire through the main harness leading to the helm and see if I can ascertain what it is.

Anyway, I'll be swapping the injectors to the original (rebuilt) ones and reassembling the intake, throttle body, etc. tonight so first thing tomorrow (or as soon as I think my neighbors won't complain) I'll hook up the hose and give it all a test. Hopefully we'll have a few answers then.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote gt40KS Quote  Post ReplyReply Direct Link To This Post Posted: July-14-2018 at 10:09pm
Originally posted by KENO KENO wrote:

In this picture of somebody's multicolored engine (with a crooked decal) you can see the hole for one sensor or switch at the left front of the lower intake, a little behind the oil fill pipe.

Then right behind the thermostat housing there is a sensor or switch right there already installed in the picture (right in front of the blue masking tape)

And you have one on the water pump.



Yeah, the first one you mentioned has an automotive style connector - no confusing it with the other two that just have threaded studs at the top. I believe the manual says that one is the sender feeds the temp to the ECM.    The one just behind the thermostat housing is the temp switch - part of the SLOW circuit.   I'm guessing the one mounted on the water pump is for the gauge? IDK ... not really any info that I can find that states exactly what this sensor is specifically used for.
But again, the crazy part is that I have 3 wires with ring terminals that are specifically for WATER temp switches or senders and only 2 senders or switches with threaded studs - remember, the 3rd device has an automotive connector so it's out of that loop.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote KENO Quote  Post ReplyReply Direct Link To This Post Posted: July-14-2018 at 10:09pm
I edited that earlier post from 7:30 a little Joe, go back to it. It has some good info from Lewy 2001 about 2 senders and 1 switch.

Lewy's post also talks about green wires
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Post Options Post Options   Thanks (1) Thanks(1)   Quote KENO Quote  Post ReplyReply Direct Link To This Post Posted: July-14-2018 at 10:15pm


This is Lewy's post, it might have all the info and colors you need

Originally posted by lewy2001 lewy2001 wrote:

Darren there are 3 water temp sensors on the GT40 engine.

1. The ECT sensor near the front on inlet manifold it is a two wire device as it has a signal return to the EEC. This is the main one for controlling fuel and ignition via computer.

2. Engine temperature gauge sender

3. Engine temp switch that puts the EEC computer into limp(SLOW) mode


The engine EEC Slow temperature switch is located here:-


It is more obvious on my engine as there is a tee piece for the heater.
The temperature gauge sender is on the engine water pump.
The switch is either open circuit or short circuit while the temperature sender varies its resistance with the temperature of coolant.

I bet they have the wiring to the SLOW temp switch and temperature gauge crossed over. The SLOW temp switch should have one green wire and one brown wire with black tracer on the single terminal(i.e. 2 wires). The green wire goes back to dash engine check light. The brown/black wire goes to pin 24 on ECU to put computer in SLOW mode. The wire on gauge temperature sender is more of a tan wire with no tracer. I think they have this wire on temperature switch and the brown/black wire on gauge sender. There is also the possibility of the sender and switch being mixed up and now in the wrong location.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote gt40KS Quote  Post ReplyReply Direct Link To This Post Posted: July-14-2018 at 10:18pm
AH HAW ....   that's the post I was looking for but couldn't find!   
Should all flow very nicely now    

Thanks Ken! ( and Lewy )
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Post Options Post Options   Thanks (0) Thanks(0)   Quote KENO Quote  Post ReplyReply Direct Link To This Post Posted: July-14-2018 at 10:20pm
Thank Lewy

If I'm understanding all this, I think your ECM wasn't getting a water temperature signal before and your slow and alarm circuit were disconnected

Carnac says you'll have a better running engine now
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Post Options Post Options   Thanks (0) Thanks(0)   Quote gt40KS Quote  Post ReplyReply Direct Link To This Post Posted: July-14-2018 at 10:23pm
That I did .... thought of that after hitting the post button. Edited now, but yes, THANKS Lewy !!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Gary S Quote  Post ReplyReply Direct Link To This Post Posted: July-14-2018 at 10:47pm
Originally posted by gt40KS gt40KS wrote:

   I ordered the correct ones from NP yesterday just to be sure.


You should have said something Joe some of those are just Ford parts. NP gets 79 bucks for the water temp sensor,nos oem on ebay is 18 shipped Ford part # F2AZ-12A648-A.
Air charge sensor is F2DZ-12A697-A. Ebay nos oem 18.50 shipped. MAP sensor E7DZ-9F479-A, NP is 259.00, ebay has an nos oem one for 80.00
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Post Options Post Options   Thanks (0) Thanks(0)   Quote gt40KS Quote  Post ReplyReply Direct Link To This Post Posted: July-15-2018 at 2:09am
Thanks Gary .... I've already gotten the most expensive ones from RockAuto - cheap(er).   The only 3 I ordered from NP were the water pump sensor, temp switch and oil switch.   Together the price wasn't too bad and now at least those 3 will be correct, original CC parts.

Look at that Pete ... I'll be installing at least a few original parts !   
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 8122pbrainard Quote  Post ReplyReply Direct Link To This Post Posted: July-15-2018 at 7:45am
Originally posted by gt40KS gt40KS wrote:



Look at that Pete ... I'll be installing at least a few original parts !   




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Post Options Post Options   Thanks (0) Thanks(0)   Quote KENO Quote  Post ReplyReply Direct Link To This Post Posted: July-15-2018 at 8:42am
Joe

If your ECM wasn't getting a signal from the sensor before and now it is, your idle might just be normal now too.

See page 2A-22 and 23 of the big manual for an explanation why.

An out of range signal from the ECT sensor (or a few other sensors) will cause the ECM to default to 800 rpm

If the switch was feeding the signal to the ECM, it was definitely "out of range"

With the sensor feeding it, things should improve as far as the ECM controlling the air/fuel ratio too along with the idle speed.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote gt40KS Quote  Post ReplyReply Direct Link To This Post Posted: July-15-2018 at 4:39pm
Got everything reinstalled last night and this morning and just ran the boat on the hose. Happy to report that the rolling idle and extreme surges are gone. Well, almost gone. There still seems to be a slight issue while coming off a higher rpm, but it only lasts for a second or two and isn't even close to as bad as I've ever experienced with this boat. The slight rolling doesn't occur every time but when it does it's only 100-200 rpm and again settles to a rock solid idle after only a second or two.   
So after warming to operating temp, I decided to check the timing. Good thing because it was off by quite a bit, probably because it had been set while in limp mode evidently. I'd post a video but I'm not quite sure how to do that yet.   

I've read a lot of posts describing the issue and it seems when the boats were new, and for the first few years thereafter it wasn't a problem. But as the GT40 engines aged many, or even most have developed the issue. Finding a post on PN from last July through a link that Ken had posted, it appears that the newer e300 program file for the ECM's may have solved the problem, but as yet no one has posted the file that I can find.

Anyway, on to the next - and hopefully final issue - of the tach issue.   Yes Ken, you were correct. The tach is a bit off ... but that is a matter for another thread
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Post Options Post Options   Thanks (0) Thanks(0)   Quote KENO Quote  Post ReplyReply Direct Link To This Post Posted: July-15-2018 at 4:53pm
Well let's get with the program Joe

I'm on the edge of my tube waiting for the next thread   

Not behind the boat, just floating in the water Pete
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 8122pbrainard Quote  Post ReplyReply Direct Link To This Post Posted: July-15-2018 at 5:05pm
Originally posted by Gary S Gary S wrote:

You should have said something Joe some of those are just Ford parts. NP gets 79 bucks for the water temp sensor,nos oem on ebay is 18 shipped Ford part # F2AZ-12A648-A.
Air charge sensor is F2DZ-12A697-A. Ebay nos oem 18.50 shipped. MAP sensor E7DZ-9F479-A, NP is 259.00, ebay has an nos oem one for 80.00


NP gets $4.68 for a galvanized pipe drain plug for a Walters V drive. Oh, wait, maybe that's a super special super precise part that's made only for Walters like their super special super precise bearings!!


BTW, it's $ .84 cents at the HD!!


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Post Options Post Options   Thanks (0) Thanks(0)   Quote Gary S Quote  Post ReplyReply Direct Link To This Post Posted: July-15-2018 at 5:23pm
Get ahold of Tom Franscioni on Planet Nautique,he is the one that downloaded the 300m tune off of his and can burn you a chip. You then have to get yourself a ECM from a Mustang (C1A1). He can also burn the older 290 tune if you desire. Original PN thread
I sent him the chip direct from Moats so we weren't sending it back and forth
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Post Options Post Options   Thanks (0) Thanks(0)   Quote gt40KS Quote  Post ReplyReply Direct Link To This Post Posted: July-15-2018 at 6:45pm
Originally posted by Gary S Gary S wrote:

Get ahold of Tom Franscioni on Planet Nautique,he is the one that downloaded the 300m tune off of his and can burn you a chip. You then have to get yourself a ECM from a Mustang (C1A1). He can also burn the older 290 tune if you desire. Original PN thread
I sent him the chip direct from Moats so we weren't sending it back and forth


Hi Gary, yeah that's the thread I had been reading. Thing is the word must be out about the C1A1 because the ONLY source on ebay is now charging a whopping $250 for those. However, the original poster of that thread said a guy could also use a D1L1, evidently same base hardware. I located and ordered one of those from ebay for $40 and the moates website has not only the chips ($75) but the programmer ($85) as well - probably order those soon as well   

I'm still not convinced that my ECM is "all there" if you know what I mean, so It'll be good to have a spare readily available.   Although I did download the e290 bin file I think I'll contact Tom to see if he can email me the file for the e300 because if i'm going to have a spare, I might as well have one with the newer file   
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Gary S Quote  Post ReplyReply Direct Link To This Post Posted: July-15-2018 at 7:42pm
Boy I'll say the word must be out I think I paid 80. I had a 290 burned because at the time that was all Tom had from the original poster. He bought the programmer and then downloaded the 300 off his own boat. Here is the original post from EECTuning.org
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Post Options Post Options   Thanks (0) Thanks(0)   Quote gt40KS Quote  Post ReplyReply Direct Link To This Post Posted: July-15-2018 at 11:19pm
Some very good reading Gary. Also the original thread that you and Ken had posted earlier. A lot of it is a bit over my head though - Never was very good with computer code.
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