Need some help with engine temp sensors 6.2 and 6.5

[fullsizeBlazer]

Hi again,

I'm currently rewiring my truck and have some minor problems:

I have a 1998 6.5 TD which I put into my 84 K5 Blazer.

Additionally I have a 1988 6.2 Diesel wiring harness.


Well here we go:

I do not know which temp sensors I need.

I already got me the matching, older style temperature sender that is located on the left (driver's side) bank.

http://s03.trixum.de/upload2/z/r/zr58VX4ZQ0WT129025079353S.jpg

As far as I figured it out, I still need a second temperature sensor for the glow plug module. As I'm not able to use a fast idle solenoid due to the water pump outled modifications, I won't need a third sensor.

Basically, my question is, what the glow plug temp sensor looks like and where it is located?

On my 1998 engine there is one sensor in the water crossover and one on the left bank (front) where the old style sensor is supposed to go.

Maybe it is that one?

http://s03.trixum.de/upload2/2/E/2EYKwfornDzi129025106821S.jpg

[fullsizeBlazer]

Finally here are some pics of my engine:

The next problem is that I do not know which pigtail is the correct one for the temp sender I'm looking for:


http://s03.trixum.de/upload2/i/H/iHlkerX2mhP7129025122698S.jpghttp://s03.trixum.de/upload2/1/j/1jDdBaiceyUG129025123462S.jpg


The 1985 wiring diagram says that the connector of the temp sensor has a yellow and orange wire and it should be located somewhere behind the intake mainfold.

Thanks a lot for your help!


Greetings from Bavaria

Flo

[fullsizeBlazer]

And here's a pic of the diagram with the two sensors/sending units

http://s03.trixum.de/upload2/P/x/PxNnZSIvYKMw129025162518S.jpg

[Robyn]

The sensor in the LH head is for the temp gauge only.

The sensor in the RH head (rear RH side) is for the cold advance.

Your wiring harness may have this up in the water crossover.

Your 85 chassis should use the later style glow controller (one single unit on the back of the engines LH side)

Really all you need is a cold advance switch GM part # 10154649

This allows power to the cold avance and the fast idle solenoid until the engine gets up to about 110F temp.

You can fashion a bracket for the fast idle use, even with the dual stat housing setup. Just gotta get creative, I have seen it done.

The later trucks use a coolant temp sensor in the crossover that feeds info to the ECM but your truck will not have this.

Keep it simple.

The glow plug controller for the 85 will work sweet.

The 85and later had a glow plug in hibit switch in the RH rear top water port. This stopped the glow plugs from coming on unless the engine was nearly COLD.

Bad idea. If your harness has this as does the glow plug controller, just jumper the two wires and forget it. Allow the plugs to cycle any time there is a KOKO.

Other than that the oil pressure sender from the 85 engine will work fine on the new engine.

Your pretty well set.

Missy

[fullsizeBlazer]

Hello Robyn,

as always: thanks a 1000nd times for your help! :):)


Well, now I just need to figure out which connector is the right one for the cold advance switch & to find a place to install that switch. -> According to Rockauto.com, it is 1/2 NPT. I hope I can install it in the new crossover where the newer style sensor is located.

[Robyn]

You can install the advance switch in the crossover but, depending on the wiring harness and which engine it came from, you may have to lengthen the wires.

If you are using the older harness just screw the advance switch into the RH rear (side ) port on the RH head.

Best to use the 85 wiring and forget the sensor in the water crossover, just plug that port.

The 98 had a "Coolant temp sensor" there to feed info to the Computer.

The 85 is far simpler with just a switch to put 12V to the cold advance on the IP and the fast idle.

This switch is either on or off and it cuts power when the engine reaches about 110F (coolant temp).

The 6.2 was a very simple engine up through about 1986 after that even these engines were fitted with a simple computer that controlled the EGR the Glow system and the lockup on the converter (700R4 trans)

I really like the 85-86 systems as they were almost trouble free.

These engines were equipped with a Glow plug inhibit switch that was screwed into the RH head up on top and the switch would go south leaving the glow plug system DEAD :eek:

Had that happen once on a trip. It was cold and snowy and the rig would not start.
I jumpered the inhibit switch with a paper clip and then taped the thing up with duct tape.
That little fix was there when I sold the truck, 5 years later. :)

The glow inhibit was a bad idea. It was a good concept but caused more troubles than it was worth.

Good luck

Robyn

[fullsizeBlazer]

Hey Robyn,

thanks again for helping me with this issue.

I talked to the guy I got the engine harness from, he said it actually is a late 1989 K5 Engine harness.

I read somewhere that they dropped the glow plug inhibit switch in 88 plus models but I am not sure.

With your help I already was able to figure out where I have to plug in most of the connectors.

I already got me a newer style glow plug connector and ordered the switch you gave me the part number.


Here are some pictures of the connectors I have no idea what to do with:

1. The pink one is for the injection pump but the connector that's circled red is still unknown to me ?? Maybe it is the one for the glow plug temperature sender ????

the two wires going to the connector are dark green and yellow with a fusible link I suppose.

I think this could be the one for the switch you sent me the part number.


http://s03.trixum.de/upload2/n/W/nWXCOlRaYDNq129068277924S.jpg


I found following pic on the internet. Connector looks like the one in the pic above but I'm not sure if this connector is supposed to go to the glow plug inhibit switch?

http://i35.tinypic.com/168aant.jpg

2 Here's the second one, located on the right engine bank too. Maybe it is for the throttle position sensor (I'm not planning on using a TP sensor as I converted the th700 with the transgo kit to hydraulic lockup)

http://s03.trixum.de/upload2/c/g/cgG0lt8nzfOW129068303268S.jpg

[Robyn]

I can't tell too much from your pix and the colors do not match what I have in my 87-89 and 91 books

The Blazer and Burbs use a different harness than the C/K trucks during the 88 and later time frame.

The harness for the IP should include a large pink wire that connects to the Fuel solenoid (on/Off)
The two small green wires with plugs that are in series and close together connect to the fast idle and the cold advance solenoid.

The Brown and yellow wires could be from the glow inhibit.

Robyn

[KidKodiak]

Interestingly, I'm learning more about my no start problem from this thread. Thank you both. Robyn, you are fantastic. Your knowledge is by far more than anyone else I've encountered.

I have two questions regarding your last post:

"The harness for the IP should include a large pink wire that connects to the Fuel solenoid (on/Off)"

- Where is this fuel solenoid located? I traced this wire back to the firewall of my 1985 3/4 ton Suburban (J code).

Also:

"The two small green wires with plugs that are in series and close together connect to the fast idle and the cold advance solenoid."

I noticed two small green/light green wires with plugs, running the length of the sidewall. But the two plugs aren't connected to anything. It kinda reminds me of a collapsed bridge: What connects the two? Or does one connect to the fast idle, and the other connect to the cold advance solenoid?

Thanks again.

[Subzilla]

The fuel shutoff solenoid sits right on top of the injector pump and should click when you apply a hot wire to it, if you want to test it. This will have a larger connector than the HPCA and fast idle connectors. The HPCA connector sits down low on the passenger side of the IP and the fast idle sits higher but still on the passenger side of the IP. The two green wire connectors in series simply connect individually to the HPCA and the fast idle. Nothing complicated here, thank goodness.

[KidKodiak]

I did a google search for "HPCA 6.2L." This is a posting I found from a different forum that came up.

"2. Throttle Position and IP "Housing pressure cold advance" switch (HPAC). It is a 2 wire temperature on/off switch that screws into the water jacket on rear passenger side of head."

I think he is referring to this object in fullsizeBlazer's post below. Can you help clear up my confusion? Thanks.

Update: I think I've identified this piece as the Glow Plug Warning Switch from NAPA's website.

http://i35.tinypic.com/168aant.jpg

[Robyn]

Sidewall ????

Not sure what you are refering too????

Robyn

[fullsizeBlazer]

Hi again,

I've got not much time now ;) so here we go:

The fuel shutoff solenoid should be installed within the injection pump.

[KidKodiak]

Thanks Robyn. I have no idea why I wrote "sidewall." I must have been distracted. Sorry for the confusion. That wire (actually two green wires) runs the length of the firewall.

The solenoid for the injector pump, might that be named "Idle Stop Solenoid?"

fullsizeBlazer, did you mean it is installed with the injection pump, or inside the injection pump?

[Robyn]

The Idle stop solenoid is the little unit on the outside of the IP that acts as the fast idle. (small green wire in the engine harness, with one connection to the cold advance and oen to the solenoid)

The large pink wire hooks to the very top of the IP to the fuel shut off solenoid (turns the fuel on when you switch the key on)

The green wires that run across the firewall I believe are for the heater OR ???
Your original 84 harness should be used as a guide.

Missy

[KidKodiak]

Thanks, Missy.

So the idle stop will not cause my problem. But the fuel shut-off solenoid will. Am I on track?

Ryan

[fullsizeBlazer]

Hey KidKodiak,

inside, of course:rolleyes: sorry.

[KidKodiak]

Ok, thanks. Today looks like it's gonna be sunny and relatively warm, so I'll see what I can do to get it running today. May the force be with me.

[fullsizeBlazer]

Hey Kidkodiak,


here's a picture (bad quality) of the pink wire & connector you have to run to your IP:
http://s03.trixum.de/upload2/g/e/geajwxW0rpFX129101805772S.jpg

[fullsizeBlazer]

@Robyn:

I finally was able to figure out which connector is for the GP temp sensor. Thank you so much for your help, I really learned alot about wiring during the last few days.

:cool::cool:

Greetings

Flo

[Robyn]

Here is some good info. I was working on an 87 Burb diesel I am using as a Donor truck and checked out the wires.

Your piccy a couple posts back

The yellow and brown wire (with plug) goes to the temp sensor in the Rh water outlet port up front.

The Pink wire goes to the fuel solenoid on the IP

The two little green ones go to the cold advance and the fast idle.

The other wire with the large eye goes to the alternator Plus stud and the smaller ones with the narrow gray plug goes to the alternator on the side.

Seems that the later engines moved the cold advance switch up front.

The early ones had it in the back.

Hope this helps

Missy

[fullsizeBlazer]

Hey,

thanks for confirming my knowledge. That's exactly how I figured it out last weekend.

Now I only have to wait until the cold advance switch arrives

&

To jumper the yellow & brown wired connector that is supposed to go to the temp sensor in the RH.

By the way,

I also got me a matching adapter for my 100 amp later model alternator.... The last one they had at amazon.com :D

For the records/ in case someone else needs that kind of adapter:

It is:

Delco 8078/GM 12102921 if you have a volt gauge or
Delco 8077/GM 12083462 if you have an "idiot" light.


Greetings and happy dieseling

Flo

[Robyn]

Jumpering the temp switch will make the Cold advance system work but do not leave it on for more than a few minutes.


Missy