[truckr65]

Hey again y'all,

The truck has been sitting for two weeks while I changed the water pump, fan clutch and belt tensioner.

After finally finishing and hooking up the batteries again, I eagerly jumped in and flipped the key in the ignition - but something was off. The WTS light never came on. I didn't think much more of it, and tried starting the engine. It cranked healthily, but never started. That was when I knew I had been struck by the WTS ghost.

So, all jokes aside, this has been buggering me all day now. I can't for the life of me get the WTS light to come on.

Diagnostics

WTS light - does not come on even for a millisecond.

Glow plug relay/controller - clicks intermittently (every 3 to 5 sec). Constant 11.7v to 12v on post to battery. -0.02v on post to glow plugs, but jumps to 11.7v to 12v every time the relay clicks. Glow plug relay is a STANDARD MOTORS RY383 less than 2 years old.

Grounds - I thought I had found the culprit with a bad glow plug relay ground. Cleaned, swapped and soldered to no avail. I soldered the glow plug relay ground together with 3 other ground cables in the same vincinity and bolted it to the engine. I also added extra grounds from both driver and passenger batteries to the engine.

Lift pump - Sound like it always did. No observable change to when the truck operated normally.

Batteries - Less than 1 year old high quality AGM batteries.

Fuses - Checked fuses under hood and in cab. None blown. Whats weird though is that the fuse under the hood designated for glow plugs has never been there. The metal connectors in the fuse block is missing, so it's not possible to put a fuse in there. The WTS light came on before, and the fuse has never been in there since I bought the truck.

Battery cable - beefy welder cable, less than 2 years old.


Pictures

Thoughts

I did get a medium spark when I hooked up the alternator to the battery. I thought I might have blown a fuse, but none were blown.

Any input is greatly appreciated. I'm currently not well enough equipped to battle this WTS ghost by my self, so any guidance will be of immense help.

 

[truckr65]

Problem Solved ✔
Thanks to the knowledgable Glagulator (and also you Tommygunner), I was able to get the truck running again.

If your truck is experiencing the symptoms described above, I highly recommend you to read through Glagulator's detailed posts - they helped me immensely.

I'd describe the issues I've had as "multifaceted", and the combination of them resulted in what my truck experienced.

#1 Inadequate Grounds
As I disassembled the accessory bracket I must have pulled loose a bad ground splice from the engine harness. I "fixed" it by re-splicing them and mounting the new ground splice in a "better" location.

Now, I don't assume you're a dumbass like me - but that bracket the new ground splice is mounted to appears to be aluminum. This resulted in an insufficient ground for the Wait To Start Lamp Control Circuit and also throwing the P1643 code.

#2 Possible Poor Contact in PCM Connector
After grounding the wires properly, I still didn't have a working WTS lamp right away. I sprayed some contact spray in the light blue PCM connector, and turned the key with the connector disconnected, before plugging it back in. WTS lamp came back on, but the truck was still in a NO START state.

#3 Bad PMD
As a source for many 6.5L headaches, my grey Stanadyne PMD located in the bumper had gone bad. I luckily bought a cheap Chinese PMD off a guy for super cheap about a year ago, so I swapped that in and the truck started right up. And yes, the lettering on the box was even in Chinese. And yes, I've ordered two brand new legit Stanadyne PMD's.

Thanks Glag - I wouldn't have pulled through this without your guidance. I hope I can rely on your guidance in the future as well!

 

[Glagulator]

Have you ever seen your WTS lamp work?
Has the gauge cluster been replaced?

 

[Tommygunner]

Scan for trouble codes?

 

[truckr65]

Glag: The lamp used to work all the time, no problems. Gauge cluster not been replaced. If it was simply a problem of a bulb not turning on, I should at least be able to start the engine.

Tommy: Codes are P0238 and P1643 - nothing related as far as I can tell.

 

[truckr65]

It May Be a Ground Issue After All? (Grounds, grounds, grounds...)

In the original post I said that "I soldered the glow plug relay ground together with 3 other ground cables in the same vicinity and bolted it to the engine" - well, turns out that all the 4 "ground" cables I soldered together may not actually all be ground cables.

So I cut them open again. After the cut was done, I no longer get a clicking from the glow plug relay when the key is in the start position, where I'd usually see the WTS light.

The Cables

These are the cables I soldered into a giant ground cable and bolted to the engine.

Now, I'm no electrician, but I read the cables voltage individually with the key in the on position, where I would usually get a WTS light. I also tried tracing the wires back to where they came from, but that is a helluva lot easier said than done.

C and D has a constant 9v to 10v and traces to the left towards the passenger side.

A has a constant 5v and traces to the glow plug relay ground wire in the connector. It also splices with 2 wires going to the drivers side, and 1 wire going to the passenger side.

B has a constant 9v to 10v and traces towards the drivers side.

Could anyone help me identify these wires? And what should I do? Should I try to ground them individually beginning with A and try too see if I get a WTS light one by one?

 

[Tommygunner]

Code P1643 is totally related to your problem, P1603= Wait To Start Lamp Control Circuit
Could be caused by:
Burned out Wait To Start Lamp.
WTS light circuit is open or shorted to ground
Wait To Start Lamp circuit poor electrical connection.
Faulty Glow Plug relay.

You have a problem somewhere in the circuit .PCM uses feedback from the Glow Plug Relay to turn on the WTS light.
Also the Glow plug relay should energize the glow plugs for quite a bit longer than 3- 5 seconds on a cold start.

 

[truckr65]

Thanks Tommy - could the fact that I have a constant voltage of 5v coming from the glow plug relay ground cable mean that I have a wire shorted to ground?

As I said, I'm no electrician, but should ground wires carry constant voltage like that?

 

[Glagulator]

A = ENG. GROUND - 12ga. BLK - many grounds
B = ENG. GROUND - 10ga. BLK - ABS
C = ENG. GROUND - 18ga. TAN/WHT - PCM
D = ENG. GROUND - 18ga. BLK/WHT - PCM

They can all be spliced together, but wait.
There is a 1 pin connector that comes off the 15 pin
connector at back of the engine, that harness runs
under the intake, that is the ENGINE HARNESS.
That 1 pin is the WTS signal. The 1 pin conn. side
that goes to the GP harness is a FUSIBLE LINK.
Make sure that conn. is connected and the FL is good.

There is no GLOW fuse on 98-up 6.5’s.- handled by the FL.
On your 99 the GLOW signal from the 1 pin conn.
goes to the PCM, the PCM then sends a GROUND
to the WTS LAMP. The WTS LAMP always has 12v.
going to it when the key is ON.

As long as the ground wires are connected to whatever
they go to you will get a voltage/continuity reading.
Unplug the conn. on the GPR and check that wire again
to see this,( if it has been isolated from any other grounds
and is not shorted to another wire).

If you can disconnect the 3 PCM connectors you can do
some testing to see what is going on, BUT do this
BEFORE you splice all the grounds.
If you decide to do this I will guide you.

FYI, never insert anything into a female terminal except for
the correct male mate terminal. They are easily damaged
and you can end up with a nightmare of intermittent electrical
problems.

When you turn on the KEY does a SECURITY lamp in the upper
right hand corner of the gauge cluster come ON for a few seconds then go out?

 

[truckr65]

Glag, this is gold! Thank you so much!

I just came back inside, the last thing I did was to open the 4 ground cables I had spliced together and individually ground them to the engine.

The security light does come on for a few seconds, here is a video of the cluster.

Here is a video of the GPR.

Plan

Check that the 1 pin connector for the WTS signal is connected and in good shape.

Follow the wire from the 1 pin connector and make sure the wire and fusible link is isolated and in good shape.

Confirm that the ground wire is connected and seated properly at the GPR connector. Double check that this wire is in good condition and is isolated.

Is the 3 PCM connectors located on the very drivers side of the firewall? Is it the same connector that the driving lights/far lights wires comes out from?

Thanks again Glag - this is the very reason I'm thankful to be a part of this community.

 

[Glagulator]

The GPR does that when the PCM loses 12v. battery.
It will start cycling correctly after 12v. batt is restored,
and any other problems are fixed, and cranking the starter
has been cycled a few times.
Just FYI, the security system may or may not get triggered before
you get your problems fixed. If that happens it will need to be reset.
Not a big deal, if the SECURITY lamp stays ON or starts flashing then
the engine will seem to start for a second then die.
This would be the last thing to deal with.
Notice how some of the gauges are not moving and the fuel gauge is going to max?
That is due to loss of ground, the ground wires you have disconnected.

 

[truckr65]

The sun is setting, so I'll have to continue the battle tomorrow.

Following the pink cable from the GPR connector and tracing it to the drivers side is a real PITA - I'd much rather install a new water pump again, that's for sure!

Is this the 1-pin connector you mentioned Glag? Seems to have been unconnected for quite some time, a lot of dust inside the connector.. and no male end to be found...

Also, quick question (which might be a very stupid one), but what does the black box in the picture below do? A few weeks ago I followed the cable that runs out of it, and saw that a few of the wires inside it wasn't making contact, so I spliced them all up individually (4 or 5 wires of super small gauge and of various colors if I remember correctly). The wire seems to plug into a connector at the intake.

 

[Glagulator]

The heavy cable from the GPR goes to the power lug on the UHFRC, the fuse relay box.
It also has an FL on it where it connects.
That conn. you pointed out is the PRIME lead for the lift pump.
Apply 12v. and the LP will run.
The black box is not a GM part, where does the cable go?

 

[truckr65]

Just got back from work - I'll check where that black box on the firewall connects to on the engine.

The heavy cable from the GPR to the UHFRC has a fusible link - I will check that one now, but I believe it should be more or less intact because I can read 12v at the post on the GPR?

There's a pink cable going from the GPR towards UHFRC which I assume connects to the 1-pin connector mentioned.

I'll check this one too.

Any final tips? What happens if the pink cable to the 1 pin connector is intact?

Sorry for being a dumbass, heading out to wrench some more now..

 

[Glagulator]

The PNK wire is 12v. ign.
The 1 pin conn. has a brown wire and it does not connect to the GPR.
See the 1 pin conn. coming off the 15 pin conn. in this image?
That is the GP signal wire, the other end connects to the glow plug harness.

https://www.dieselplace.com/cdn-cgi/image/format=auto,onerror=redirect,width=1920,height=1920,fit=scale-down/https://www.dieselplace.com/attachments/harn-eng-oem-up-01-jpg.651000/

 

[truckr65]

Located the 1 pin

Thanks Glag - that last image helped me locate the 1-pin connector. I unplugged the connector, and both male and female end seemed to be in very good shape. I can't remember if it was the female or the male end of the connector that bolted on to the GPR. I measure the end to the GPR and it read 11v "in-between clicks". As if the GPR clicks on it reads 11v and when it clicks off it reads -0.02v.

I seated the connector again and opened the brown wire a tiny bit after the wire comes out from the main 15 pin connector, and it voltage tested to the exact same result. I think the connectors themselves is in good shape. That brown wire goes along side the other wires towards the passenger side. Is there another place I can make a reading on the wire to triple check that the wire is good?

The mysterious black box

Remember the mysterious black box from the last post?

I traced the wires towards the intake manifold, and the results are in.

From the black wire coming out of the black box, we have the following

A green, brown and yellow wire. Brown and yellow connects to the white connector, which goes into (MAP sensor?) the small black rectangular box on the intake.

Green goes

To the connector the arrow points to above. Is this a thermometer sensor?

Now, ALL the wires is in seriously bad shape

So, could this in fact be the culprit?

That I "fixed" some frayed wires inside the black tubing coming out from the mysterious black box?

Suggestions going forward? I could try to fix those frayed cables in the above picture, and see if it has any effect. Or should I try to follow the brown cable all the way from the 15-pin connector and see if the culprit is in a bad wire there?

I don't really get that the culprit would be in the brown wire. It's been fine all the way until now, I didn't do anything to damage it as far as I know. And I "fixed" the wires coming from the black box before letting the truck sit a few weeks before the WTS light disappeared. The WTS was on in the period after I fixed those cables though, but the car never sat unstated for more than a day during that period.

I'm really clueless at this point.

 

[Glagulator]

Are there any add-on gauges in the cab?
Have you removed the box to see if wires go inside?
It must be either for add-on gauges or a boost fooler.
At this point I would test the WTS lamp.
The most thorough and best way is to test it from the PCM
connector where the signal originates.
Do you want to do this?

 

[truckr65]

There are no add-on gauges in the cab. There aren't any visual signs in the cab that add-on gauges have been installed either (screw holes etc.)

I haven't removed the wires yet. It's on my list for tomorrow.

If the WTS lamp is faulty - would this result in a no start? I'm not really sure what I've done that's resulted in this. Could this have been a result of me sparking a cable when I installed the alternator?

I'm going to go over all grounds once more, possibly try to add a ground on the alternator.

If this yields no results, I'm ready and want to test it through the PCM. It sounds sketchy as hell, but I'm assured to have professionals like you to guide me Glag. Thank you again for all the wisdom!

 

[Glagulator]

Open the box if you can or unscrew the box from the firewall to see if there are any wires going inside.
It's not the fact that the WTS bulb may be burned out, it could be a wiring problem or who knows.
Some engines will start right up without the glows and some will not.
If the test lights the WTS lamp then we look elsewhere for the problem.
The WTS lamp test is not hard to do.
If you GROUND this BLUE wire (position C7 on the light blue connector) with the KEY ON, the WTS lamp should light up.

 

[Tommygunner]

The Black box looks like a boost fooler to me. It is most likely the reason for the P0238 Turbo Boost Sensor Circuit High Voltage. trouble code you have. That is a horrible hack job on the wiring.
There may be some kind of knob or control switch in the cab. To regulate the boost
Also have you done a trouble code scan after you shorted the alternator when connecting? Need to make sure the PCM is OK.