Water Temperature Sensor Functionality - S-10 Forum
 
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post #1 of 23 Old 06-02-2019, 12:49 PM Thread Starter
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Water Temperature Sensor Functionality

I have put a rebuilt engine in my 2000 Oldsmobile Bravada. I exchanged my heads at a local machine shop for a set of rebuilt ones. There is a square head plug that occupies the threaded hole where my temperature sensor goes. That stubborn plug rounded out the square and never broke loose. My question is does the water temperature sensor just operates the gauge or does it send information to the ECM as well?

Also, my tachometer isnít working. Where doI begin my trouble shoot for that?

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post #2 of 23 Old 06-02-2019, 12:53 PM
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Re: Water Temperature Sensor Functionality

there are 2
one for gauge ,one for ECM.
Buy only Delco,others are just too flaky.
apply some heat to the plug to aid in removal
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post #3 of 23 Old 06-02-2019, 01:36 PM Thread Starter
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Re: Water Temperature Sensor Functionality

Thank you for the reply. The sensor thatís not plugged in is definitely the one for the gauge then. Curiously, where is the location for the one that provides information to the ECM.

Iíll try your heat method.
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post #4 of 23 Old 06-02-2019, 01:39 PM
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Re: Water Temperature Sensor Functionality

just under the brake system on drivers side head
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post #5 of 23 Old 06-02-2019, 02:00 PM
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Re: Water Temperature Sensor Functionality

A 2000 only has one sensor. It is in the driver's side head.

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post #6 of 23 Old 06-02-2019, 05:09 PM Thread Starter
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Re: Water Temperature Sensor Functionality

Does that sensor feed information to the ECM?
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post #7 of 23 Old 06-02-2019, 05:26 PM
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Re: Water Temperature Sensor Functionality

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Originally Posted by Bilster View Post
Does that sensor feed information to the ECM?
Yes. IIRC, the pcm sends the temp signal to the gauge.

1992 rcsb 4.3,at 357,000 miles. Rust in Peace
2000 Jimmy 4x4 4dr. 255,000 miles
2002 rcsb, 2.2 at, 289,000miles
1967 C10
2006 Colorado
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post #8 of 23 Old 06-02-2019, 11:36 PM
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Re: Water Temperature Sensor Functionality

It's too bad you weren't aware of the issue before you installed your heads. I bet if you look on the rear of the passengers side head there is a new plug in it. Assuming the pair came off the same engine prior to rebuilding.
It's something I always watch for when replacing a pair of heads. If you swap sides that plug can be a PITA to get out because that plug was put in at the factory 20 years ago and put on the rear passengers side and never touched. While the head on the drivers side had a brass threaded sender which comes out easily. No rust.
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post #9 of 23 Old 06-03-2019, 12:02 AM
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Re: Water Temperature Sensor Functionality

The 3/8' drive drive won't do it....obviously.. I bought a set of square drives from Harbor Freight and it had the correct size. IIRC right off hand it was. I'll check tomorrow.

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post #10 of 23 Old 06-10-2019, 12:59 PM
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Re: Water Temperature Sensor Functionality

Getting rusty things loose- Go to Fastenal or an industrial supply store and get toilet bowl cleaner with hydrochloric acid. The stuff is EVIL, but a good way to de-rust anything. The fumes chased me across the YARD using it to clean a driveshaft yoke, but it dissolves rust down to bare metal and will penetrate- its very thin liquid. That worked very well in loosening badly rusted seat bolts in the 78 Blazer. Itll dissolve the rust chemically.

DONT breathe the fumes, wear gloves and goggles. ITs 6.5 M, which is a fairly concentrated acid.
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post #11 of 23 Old 06-10-2019, 01:42 PM
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Re: Water Temperature Sensor Functionality

....or, get the correct drive.

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post #12 of 23 Old 06-10-2019, 04:57 PM
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Re: Water Temperature Sensor Functionality

The correct drive for the factory plugs is a 5/16 square plug bit.

Did the 2000s have the sensor in the driver's side head? or by the thermostat?

I know the 1996-1997 had it by the thermostat. I'm sure the non-EGR 2003s had it in the driver's side head. Not sure when in the middle there was the change.

And it's a single 2 wire sensor. I don't honestly remember if both wires go to the PCM and the PCM runs the gauge, or if there's two separate sensors in it, one for the PCM and one for the gauge, with two separate wires (using the head/block as ground).


Also, if you have a plug in the driver's side head, check the passenger side head and make sure you don't have an open hole there.

Every machine is a smoke machine if you operate it wrong enough.
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post #13 of 23 Old 06-12-2019, 12:58 AM Thread Starter
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Re: Water Temperature Sensor Functionality

Itís on the drivers side head. I didnít think the plug was going to be that stubborn when I installed the head. With the steering shaft unbolted at the box and the front tire off, access was easy enough. And what better head stand than the motor itself.....right? Well, I got the correct 5/16Ē plug but the Chinese unit was not up to the task. It just snapped off in the plug. The wire isnít long enough to reach the passenger side head. Itís looking like a head swap. Passenger to driver side as oldeeslayer suggested. Even though itís running good, might swap out the spider assembly to the later unit as well. Not sure. Iím planning a LS swap down the road. Iíve got the correct pan, the proper headers, and the mounts. Iím negotiating an iron front differential and I have an Explorer rear. Iím still needing a harness and a transmission that up to the task of a mildly built L33.
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post #14 of 23 Old 06-12-2019, 01:17 AM
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Re: Water Temperature Sensor Functionality

Why not just extend the wire to the passenger side??

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post #15 of 23 Old 06-12-2019, 04:32 AM
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Re: Water Temperature Sensor Functionality

Or get a better tool.

https://www.homedepot.com/p/Sunex-5-...10PC/301176558

Every machine is a smoke machine if you operate it wrong enough.
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post #16 of 23 Old 06-12-2019, 07:07 AM
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Re: Water Temperature Sensor Functionality

I wasn't suggesting you swap heads now that they are installed. I'm with Rhot on this, extend the wires. Solder and shrink wrap them as they work at low voltage.
Rockauto has a number of pigtails to choose from from $4-24. I'd pick one in the middle price range. Or get one from a junkyard. Almost any GM in that era will have one. The advantage to a JY one is you can follow the wires back a foot or more before cutting and only have to solder one point.
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post #17 of 23 Old 06-12-2019, 11:06 AM Thread Starter
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Re: Water Temperature Sensor Functionality

The idea of extending the wires did occur to me. But I had an LS swap harness that was universal. I had to extend the oxygen sensor harness and I did my very best to maintain integrity but it sends a code for oxygen sensor on that bank. I have installed high quality sensors and know itís my repair that was throwing the code. I moved the sensor bung closer, removed my wiring and resoldered a new connection. Never had a problem after. Modifying harnessing that delivers messages to the ECM is voodoo for me.
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post #18 of 23 Old 06-12-2019, 11:31 AM
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Re: Water Temperature Sensor Functionality

Well then...post 15.

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post #19 of 23 Old 06-12-2019, 12:21 PM
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Re: Water Temperature Sensor Functionality

https://amzn.com/B07JQ2ZPXQ


That's an "extension cable" for the GM 2 wire engine coolant temp sensors.

Every machine is a smoke machine if you operate it wrong enough.
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post #20 of 23 Old 06-12-2019, 12:25 PM Thread Starter
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Re: Water Temperature Sensor Functionality

Quote:
Originally Posted by Rhotpursuit View Post
Well then...post 15.
No question thatís the first course of action.
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post #21 of 23 Old 06-12-2019, 12:28 PM Thread Starter
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Re: Water Temperature Sensor Functionality

Quote:
Originally Posted by Racer-X View Post
https://amzn.com/B07JQ2ZPXQ


That's an "extension cable" for the GM 2 wire engine coolant temp sensors.
Is my harness a GM2?
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post #22 of 23 Old 06-12-2019, 12:37 PM
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Re: Water Temperature Sensor Functionality

I can't see yours from here. There are closeups of the ends of that cable shown on that page on Amazon. Look at your plug, or your sensor. If it looks the same, it should fit.

That definitely fits the sensor I have on my 4.3L, and every other Vortec 4.3L I've seen (1996-2003 or later).

Every machine is a smoke machine if you operate it wrong enough.
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post #23 of 23 Old 06-14-2019, 10:34 AM Thread Starter
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Re: Water Temperature Sensor Functionality

Thanks for the link. Ordered mine today. Connections match. Also ordered a set of US made dropped forged square sockets. A used set of Matco brand off of eBay. Iíll report the results. Thanks for all the input.
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