Where does this oval plug connect? Oil /coolant?

[ohiohc]

Hello,

I bought this '89 ck3500 from a guy that was in the middle of a few updates and just finished a motor swap.

Been looking on line for diagrams. Not exactly sure what year engine is in there. Runs pretty rough, unplugged the map and egr it cleared up and seen to run much better.

Things I know, transmission in it is a 700 R4 with speedo cable. Had to order the converter thing. Coolant gauge doesn't work, oil pressure gauge no worky either.

 

I have a little work cut out for me.

 

Thank you in advance

[LDM]

That looks like the plug for the CTS (coolant temperature sensor).  That one should be by the thermostat housing and it feeds the info to the ECM.  This not being plugged in can definitely cause issues with how it runs, as the ECM using that temp sensor to calculate spark advance.

 

The one for your non-working coolant temp gauge is in the driver side head.  It has the same style connector as well.

[ohiohc]

I appreciate the response, looking on line I found that style of plug. Indeed it did say coolant temp sensor. I purchased new sensors for head and by thermostat housing. The one by housing has a 2 prong plug, and its plugged in to harness. Now I'm all kinds of confused. The one in the drivers head has a single male blade on it.

 

I may have to talk to this guy again to see if he changed and wiring or something.

[newdude]

350 or 454?

[ohiohc]

Its a 350 CID from a conversion van. I never thought to ask if it originally came with a big block.

[LDM]

16 hours ago, ohiohc said:

I appreciate the response, looking on line I found that style of plug. Indeed it did say coolant temp sensor. I purchased new sensors for head and by thermostat housing. The one by housing has a 2 prong plug, and its plugged in to harness. Now I'm all kinds of confused. The one in the drivers head has a single male blade on it.

 

I may have to talk to this guy again to see if he changed and wiring or something.

You don't need the one in the head to make the truck run well but it seems like someone has messed with the wiring.  Always fun going through and fixing what other people decide to do to vehicles.

[ohiohc]

Comedy of errs, my friend e-mailed me the wiring schematic. Of course when I blew it up large enough to see, it became blurry. I'll get the thread updated when I figure it all out. Thanks to everyone

[ohiohc]

Also, is there any chance at all that connector could go to oil pressure sensor? I've yet to find a good pic of location. Problem for me is the truck is at my buddies shop. I'm depending on google until I get back there.

 

[LDM]

18 minutes ago, ohiohc said:

Also, is there any chance at all that connector could go to oil pressure sensor? I've yet to find a good pic of location. Problem for me is the truck is at my buddies shop. I'm depending on google until I get back there.

 

No, the oil pressure sensor is a 2 prong plug.  Those type of connectors in your picture are typically used for CTS and knock sensors.

[ohiohc]

AH, see there what you just said, my coolant temp sensor has a 2 prong plug plugged into it.

[LDM]

16 hours ago, ohiohc said:

AH, see there what you just said, my coolant temp sensor has a 2 prong plug plugged into it.

They do have those as well for the CTS sensors too, just depends on the year.  It sounds like someone might have used a whole variety on your truck.  You may end up needing to do some pin testing from the ECM to the sensor connectors to determine what is suppose to go where.  If your oil pressure sensor connector ended up in a CTS sensor, that just sounds like a whole lot of fun.

[ohiohc]

Little update, new temp sensor next to thermostat installed and working fine. Truck runs great cold, runs amazing. Warms up and won't run. I couldn't get my hands on the wiring schematic so I'm done with TBI. It'll be converted to carb today, this is going to be a local tow rig for my trailer. Thanks for all of the help.

 

I started looking around at all the hack job wiring and decided I'm not spending a week rewiring this old turd.

[ohiohc]

Conversion to carb is pretty much done. Need to hook up cruise control, loom some wires and get a hole drilled in the throttle bracket. Runs fantastic! It's going to be a nice tow rig, we still have to get the res of it put together and painted. Lets see if this works.

 

 

 

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[ohiohc]

 

[CamGTP]

Now just slap a wideband in the exhaust and really tune that carb. Dial in the proper jet sizes to get idle good, cruise for fuel mileage and a nice air fuel ratio at full throttle.