I'm new here but have been gleaning kernals of info from this site the last few days. here's my deal;

this is the second engine ive swapped, first blazer. I have almost everything hooked back up on the new engine when I ran into a problem. I was plugging in the wiring harness and I cannot find the plug for the Temp sensor that is on the drivers side of the engine, between the manifold and the valve cover. because i'm new to engine swapping I label every electrical connector when I take it off but somehow this one was not marked. obviously the label would have been on the sensor of the old engine but I never labeled it and dont specifically remember taking it apart. maybe it was never plugged in?? I dont know if the temp gauge was working before because i bought this with the issues so I loaded it up on the car dolley and pulled it home and here I am.

can some one tell me if this plugs into the main harness? if so aprox where does the wire 'y' off from the harness to plug into the temp sensor? i.e. close to the TPS etc... What scenarios would take place for it not to have the plug at all if that is possible? I opened up much of the heat shield around where I would think the plug would be but I dont see any 'bugged' or cut wires. there are however several black wires right on top the trans bell housing that are bugged together, but deducing from the bracket that holds the wire connector of the Temp sensor it seems like it should be coming out of the main harness.

my experience with wiring is limited, I can match the black to black and so on but when people start talking about OHMs and resistance im lost... but willing to learn!

 

To be clear...you have the sensor in place and you can't find the connector that goes to it? Is that correct? What engine are we talking about? For what year and model truck? Is it a 'W' or 'X' VIN mumber?

EDIT: Also, the black wires you are referring to that have the connector on it for a bolt to go thru are some of your ground wires. They attach to the rear of the heads. There's some for the driver's side and some for the passenger's side. I believe it's 2ea. with also the big fat grounding strap attached to the back of the pass side head.

 

'98 chevy blazer, vin 'w'... Donor engine is a vin 'x', we swapped the pan, oil pickup, and remote oil lines. Both the original 'w' engine and the donor 'x' engine have the temp sensor on the side of the block. I have the sensor located, and the wire runs to the top side of the engine where the electrical connector is held by a bracket, however, I cannot find a connector on the wiring harness to plug the sensor into.

Is it possible that the wiring harness was swapped at some point in the past that doesn't support this sensor? I'm not sure if they all did or not.

 

I have a '98 VIN 'W', I believe the 2 wire colors are yellow and black. Anything is possible as far as the harness question goes. My '98 was a mish-mosh of stuff from the PO.

I'm not sure I understand when you say the wire runs to the top of the engine. Can you post a pic of the wire and connector?

 

Counting from right to left (as you face the front of the engine) where the loom disappears and hooks up under the "Underhood Fuse Block Connector"...I show the ECT wires being spliced in the third splice pack in that loom. Same splice pack where the TP sensor wire comes out of.


EDIT: Just went out and looked at my truck. Definitely a plug with yellow wire and a black wire (but that goes all the way to the sensor which is why I don't understand the wire you are referring to on top of the engine). Definitely splices into the big loom the same splice pack the TP sensor comes out of.

 

I am referring to the sensor on the drivers side of the engine just above the exhaust manifold, NOT the sensor located near the thermostat. The sensor near the thermostat has yellow and black wires too, but it also has this other sensor on the side of the block that has a single black wire ran to it.

 

I cant figure out how to post pix in this thread so I made an album with about 4 pix showing the sensor and where the TPS 'y's off of the harness and there is definitely not any cut wires there, so little posibility that the harness supports this sensor? can some one tell me if some blazers only have the one sensor by the thermostat and do not have a second one on the side of the block?

 

We're talking about the same location.

Actually, on some trucks I think there is a second (?) ECT around the thermostat housing. My VIN 'W' only has it in the location we've been discussing (between #3 and #5 exhaust ports). Maybe VIN "X" has it near the thermo housing??

The wires I mentioned above are for a connector that has two prongs and a shape kind of like a mushroom.

AutoZone.com Enlarged Image

Those two wires (one yellow and one black) splice at the same location where the TP sensor (along with a couple of others) come out of the larger loom. The yellow and black wires are about 10-12" long (in a small loom) and go to the ECT sensor on the drivers side of the block. The only sensor in that area I am aware of (off the top of my head) that has one black wire is the knock sensor. On a VIN "W" it is located by the distributor.

 

Do you have a link for the album? EDIT: Disregard...didn't know you meant an album in the forum..looking at it now.

 

Seems like we have some differences then, unless I'm confused on my sensor which is not unlikely :/ I have a sensor with on yellow and one black wire directly in front of the thermostat housing... Right on the front, top, center engine. Then, what I thought was another temp sensor on the side of the block as we discussed. But this sensor, as stated, only has ONE black wire coming off of it about a foot long then has a connector on the end where the wiring harness should plug in. That is the only sensor on the drivers side engine.

However, the 'new' engine was supposedly a vin x, and the old a vin w but as stated earlier, both my engines have this sensor and both engines only have the one black wire about a foot long etc... I thought this sensor was the one that ran the gauge but maybe my other one does since it has the black and yellow wires?