Water Temp Sending unit - Team Camaro Tech
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post #1 of 13 (permalink) Old Jul 11th, 07, 06:40 PM Thread Starter
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Water Temp Sending unit

I need to figure out the best way to hook up 3 water temp sending units on my 350 TPI engine. I've currently got 2 sending units hooked up. 1 for the computer, 1 for the electric fans and I need 1 more for the cold start injector. Can anyone tell me if I can splice 2 wiring harnesses into 1 sending unit without screwing up the resistance? If I cant splice 2 together, does anyone know of a thermostat housing that will take a sending unit and still fit under the upper plenum? Engine is a 86 350 TPI.

Thanks,
Jerry
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post #2 of 13 (permalink) Old Jul 11th, 07, 11:39 PM
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Re: Water Temp Sending unit

yes. you are not changing the electrical load, per se. You can use one harness for 2 sending units. But Do not tie them to the ECM. you will confuse it.
Advice: one harness spliced to 2 sending units, 1 for fans and 1 for cold start injector. that will work.
ECM monitors engine temp. that sending unit needs to be stand alone. Good luck!

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post #3 of 13 (permalink) Old Jul 12th, 07, 04:24 AM
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Re: Water Temp Sending unit

As said, the ECM unit should be left alone. In OE set-ups: The fan switch is on the pass cyl head. The cold start inj power comes from the Bosch thermo switch just below the thermostat housing, and its on for approx 8 seconds. After timeout, it stays open until coolant is below 68*F.

Battery power to one terminal of Bosch sw, the other terminal to the inj, then other inj terminal to ground. Look at an engine wiring diagram to make sure, I'm going from memory when I had one, 85 Z/28, 4 yrs ago.

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post #4 of 13 (permalink) Old Jul 12th, 07, 07:32 AM
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Re: Water Temp Sending unit

Ev, that sounds about right.

Can the fan swtich setup for a Spal or DCC fan contorller. Sender problem solved.

They don't make TPI water necks with holes in them?

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post #5 of 13 (permalink) Old Jul 12th, 07, 10:11 AM
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Re: Water Temp Sending unit

Quote:
Originally Posted by BonzoHansen View Post
Ev, that sounds about right.
Thanks for the support!
Quote:

Can the fan swtich setup for a Spal or DCC fan contorller. Sender problem solved.
It could control the fan relay as it does now, the drvr side fan. The second fan is ECM relay-controlled for DEF & A/C.
Quote:
They don't make TPI water necks with holes in them?
I haven't seen one yet. maybe beacuse there isn't much room between the throttle body and thermostat housing. Room is tight already.

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post #6 of 13 (permalink) Old Jul 12th, 07, 11:33 AM Thread Starter
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Re: Water Temp Sending unit

Thanks for the replys. I should have gave a little more info. The wiring harness is a painless harness. The cold start injector switch is shown in the wiring diagrams as to hooking to the sending unit on front of engine next to a 2nd sending unit that is currently hooked back to the computer. Right now I'm useing this 2nd sending unit to turn my SPAL fan duel controller on and off. If I can determine that it is ok to do so, I'm gonna splice the cold iniector and Spal controller to the same sending unit, leaving the 1st sending unit only to the computer. I'll let everyone know how this works out .
Thanks
Jerry
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post #7 of 13 (permalink) Old Jul 12th, 07, 12:51 PM
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Talking Re: Water Temp Sending unit

Quote:
Originally Posted by Hot 67 View Post
Thanks for the replys. I should have gave a little more info. The wiring harness is a painless harness. The cold start injector switch is shown in the wiring diagrams as to hooking to the sending unit on front of engine next to a 2nd sending unit that is currently hooked back to the computer. Right now I'm useing this 2nd sending unit to turn my SPAL fan duel controller on and off. If I can determine that it is ok to do so, I'm gonna splice the cold iniector and Spal controller to the same sending unit, leaving the 1st sending unit only to the computer. I'll let everyone know how this works out .
Thanks
Jerry
This will work.

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post #8 of 13 (permalink) Old Jul 12th, 07, 04:50 PM
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Re: Water Temp Sending unit

Quote:
Originally Posted by Everett#2390 View Post
Quote:
Can the fan swtich setup for a Spal or DCC fan contorller. Sender problem solved.
It could control the fan relay as it does now, the drvr side fan. The second fan is ECM relay-controlled for DEF & A/C.
LOL, I meant 'can' as in 'trash, discard, remove'. My DCC controller uses a small probe in the rad - no 'sender'. I thought the spal one did too, but apparently not. The DCC has an AC trigger too, but I have yet to utilize it..

Scott from NJ. Stay thirsty, my friends


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post #9 of 13 (permalink) Old Jul 12th, 07, 05:50 PM Thread Starter
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Re: Water Temp Sending unit

I Love my Spal FAN-PWM controller. It turns my dual fans on 1 at a time, first at half speed at any selected water temp then goes to High at 2nd selected temp. warks great with the dual Spal 10" fans. All controlled by a stock style water temp sending unit at the front of the block. It is super easy to program.
I've been having a starting problem so I want to re-install the 9th(cold start injector), to see if that will help my starting, although "cold" start has to be an oxize-maron here in Az., where the overnight low is around 85*.

Thanks for all the advice on hooking things up.
Jerry
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post #10 of 13 (permalink) Old Jul 20th, 07, 07:21 PM Thread Starter
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Re: Water Temp Sending unit

In order to splice the 2 seperate units to the single sending unit.(9th injector and spal controller), how should I splice the wires together to insure that both will have the proper polarity. The injector wiring has 2 wires colored purple and tan : the fan controller has 2 wire colored green and black. Different style connectors that each would normally connect to its own temp sending unit. What is the most likely way to connect them together to insure that the sending unit sends the proper signal to both. I'm using the 9th injector type temp sending unit.
Thanks for everyones help,
Jerry
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post #11 of 13 (permalink) Old Jul 20th, 07, 07:33 PM
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Re: Water Temp Sending unit

From Everett's description of the cold start sensor, it does not sound like a normal linear sender as would be used for a gauge or ECM input?

If it works as he said (on for 8 seconds at cold start, then off until the next time the coolant is below 68) the fan controller ain't gonna be too happy with it.

What about the back of the other head, pass side between 6 & 8?

When I do my EFI swap, I fully intend to use the sender for my autometer temp gauge as the input to the ECM. Fortunately the temp enrichment on the commander 950 is completel,y programable, so I figure it don't matter if it "reads right" as long as I tell it the right thing to do at the reading it has.





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post #12 of 13 (permalink) Old Jul 24th, 07, 07:41 AM Thread Starter
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Re: Water Temp Sending unit

Well Guys, I've finally got everything wired,connected and operational. Thanks Jim for reminding me about the port between 6&8 cyl. I knew about this but it had completely slipped my mind. I used this spot and installed a standard TPI temp sensor and all seems to be working fine. My 9th injector appears to have fixed my starting issue, as the car has started easily the last 2 days without having to use eather. Thanks to all who had suggestions for me.
Jerry
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post #13 of 13 (permalink) Old Jul 24th, 07, 08:00 PM
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Re: Water Temp Sending unit







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