Dtc 13

[GMC-John]

After paying to get the fuel filter canister changed, I drove my 1994 TD home and it seemed to run great. I drove it around for another 6 miles and then home. I parked it and then the next day I went out and it totally failed to start. I checked the ALDL and it now has started to give me DTC 13-Engine Shutoff solenoid circuit fault. If the solenoid wasn't retracting then it obviously wouldn't start so I borrowed another solenoid that was verified to be good. I took my original solenoid off and bench tested it and it tested perfectly with the plunger moving quickly. I guessed that maybe there was something else wrong with it so I took the borrowed solenoid and tested it on the bench and it moved exactly as the original one by not missing a beat with 12 volts applied to it. I installed the borrowed one anyway, just because. The truck made no effort at all to start and I verified that a fair amount of fuel was heading for the DS-4. This would lead you to believe that the solenoid (s) were acting up so I jumpered 12 jolts to the two lead wires on the installed borrowed solenoid.......nothing, even though I could hear the solenoid open up when I applied power. I then checked the voltage at the solenoid connector from the truck wiring harness and it showed a a scant 2.4 volts. This may be why I am getting DTC 13 but why didn't it start when I am 99.99 percent sure that the solenoid was open? Another question is where should I be checking for a substantial voltage drop on the solenoid lead in wires? Do you suspect that the fuel filter re-do messed with the wires right next to it? Thirdly (not related), if you are in front of the engine and look at the firewall, the tranny (auto) dipstick is visible slightly at the left of the firewall. Looking farther left about three inches there is a black and a white wire emerging from the main bundle. What are these for?

[JohnC]

If the solenoid voltage is low, what else is low too? Your entire injection system could be trying to run on 2.4 volts... (This would account for why jumping to the solenoid didn't solve your problem.)

[High Toned SOB]

John i cannot answer all your q’s right this second, but here is what I would
do quick and easy.
1. Check and make sure they did everything right with the fuel canister (however since you paid someone to do that, i am ASSuming you have little mechanical knowledge, since thats a pretty easy job) Most of the ones i have seen have bare wires at the heater and wif sensor.
2. Pull the fuel solenoid and start cranking, hopefully your lift pump will kick on and you can see fuel coming up into the IP.
3. I can tell you for a fact it will run fine without a SOS at all, as i took mine out and plugged the hole a while ago.
4. By now you probably have air in the system, so its gonna take minute even when it is right. Can you splice in a fuel pressure gauge at the IP?
5. My ‘94 has will not set a CEL for the missing SOS, but it is there if i check the codes. I have taken mine out and started it, it just leaks fuel out of the hole. Thats when i decided to just plug it.
6. Is there any fuel at the filter housing when your cranking? Does the IP come on at all? I did the oil pressure bypass and big pump and all 3/8 line so its easy to hear my pump. I’d listen for yours to be “pulsing”, then go from there.

[GMC-John]

Thanks for the above suggestions and here are some answers:
1) Fuel output to the IP is substantial...maybe 4-5 ozs just in 15 seconds of cranking. This was measured at fuel input connection on IP.
2) Voltage at both banks of glow plugs is 11.9-12.2 volts during glow plug heating session.
3) External voltage was again added to the wire leads for the Fuel shut-off valve and it clicked open during starting procedure.
4) I still have only 2.4 volts on the wiring harness leading to the fuel shut-off valve but this was by-passed with the above (3) item during starting attempt.
5) remote PMD connections (both ends) checked and again replaced PMD with a brand new one.
6) The OPS was replaced before this happened and it worked beautifully.
7) There has to be substantial fuel flow through the filter since the fuel is very strong at the IP input pipe.
8) Battery voltage was 13.2 volts during test.

High Toned....I'm not sure what you mean by "does the IP come on at all". Is there a way to listen for the IP even though the engine is not running?

[High Toned SOB]

Hi john, Sorry i meant the lift pump. Down on the frame under the drivers seat. Im gonna look at a wiring diagram real quick....

[High Toned SOB]

Anything at the injectors when cranking John?

And you could be wrong on #7, just because its there doesnt mean its inside..anything from the return or injectors will tell ya that. No white smoke when cranking, right?

[High Toned SOB]

Check this out buddy, maybe it will help?




5079

[High Toned SOB]

Sorry indont know how to make that bigger. I went with a k2500 automatic, shouldnt matter....

[JohnC]

The shutoff solenoid and the fuel metering solenoid both run off the same voltage supply. Trace back toward the fuse box (fuel solenoid fuse) and figure out why your voltage is low.



3. I can tell you for a fact it will run fine without a SOS at all, as i took mine out and plugged the hole a while ago.
This might not be the best idea. A common failure mode for the FSD is full on. When that happens the PCM uses the shutoff solenoid to prevent the engine from running away. This is one of the scenarios that causes "stalling".

[Robyn]

On the 94 the batteries are wired up so the RH battery supplies voltage to the power junction block to feed the rig and the starter......the Alternator feeds the LH battery.

Be sure your grounds are both good and both positives are clean and good.

A bad ground on the RH battery will cause a severe voltage drop at the junction block.

Also check the fusible link/s that feed the junction block.

This really sounds like a voltage issue due to either a bad connection on a ground or a Positive feed.

ALSO.....there is a fairly large wire piggybacked to the RH positive cable.....maybe a #4 BLACK
This cable feeds the junction block.

Check the voltage at the firewall junction block.
You can have good voltage at the batteries and the alternator stud and very low voltage at the junction block.

The #4 power cable connects to the battery plus and then sneaks down along the engine and back up to the junction block.

If this cable connection has failed at the crimp connection on the RH battery it will fool you....


The power feeds into the engine harness are small wires and it takes only a small issue to make all sorts of problems

[High Toned SOB]

The shutoff solenoid and the fuel metering solenoid both run off the same voltage supply. Trace back toward the fuse box (fuel solenoid fuse) and figure out why your voltage is low.


This might not be the best idea. A common failure mode for the FSD is full on. When that happens the PCM uses the shutoff solenoid to prevent the engine from running away. This is one of the scenarios that causes "stalling".

John i could be wrong as my 6.5 electronics isnt the best, but my experience is no matter what, when you kill the power to the pmd, it will stop the IP from working no matter what. Cant have a (fuel) runaway if the pmd is inop. Is that wrong?

[JohnC]

That is correct, but then you're introducing the human factor into the mix. Recognize the problem, determine the fix, and implement it all before you crash or blow the engine. Also, the fuel solenoid itself has been known to stick, and if that happens nothing's going to stop it in time.

[DmaxMaverick]

John i could be wrong as my 6.5 electronics isnt the best, but my experience is no matter what, when you kill the power to the pmd, it will stop the IP from working no matter what. Cant have a (fuel) runaway if the pmd is inop. Is that wrong?

IF you are there to turn off the key (Ign. sw. powers the PMD main). When the PMD fails, it almost always goes one of two ways: Open circuit (stall/quit), or full HOT (full power to the fuel solenoid, and max fuel). The PCM will only cut the ESS (Engine STOP Solenoid) when it runs past 4500-ish RPMs, but it will, if it can. Most of the time after that incident, you can just turn the key back on and drive away like nothing happened, until the next time. The absense of the ESS will give you an idea how an improperly set Detroit fuel rack results. Different scale, same result. May need a change of undies (and a new engine).

(With normally equipped and functioning ESS)
If the runaway occurs with the tranny is disengaged, it will run up and kill --over in a couple seconds, standing there like -WTF? Most dramatic PMD runaways occur during driving, with the tranny in gear at low speed or stopped. The torque converter prevents the overspeed when the driver mashes the stop pedal (for a while). Engine runs at full power, driver stands on the brakes or drives in very fast circles in a parking lot until they throw it out of gear (engine revs then kills), hit something (should have been a NHTSA recall, but alas), or turns off the key. Makes for an exciting trip to the grocery store.

[GMC-John]

Thank you all for your comments. I don't plan on eliminating the fuel shut-off valve if for no other reason that it apparently works if it has the full 12 volts, and I have two solenoids.
I have checked carefully about voltage losses in wiring and find that all of the terminals in the junction box register the exact same as the battery terminal voltage so, sadly, there is no easy fix on that. Even the ground straps measure zero loss measured from both the ground wires as they connect to the block. The block itself shows no resistance loss through the grounding connectors.
What I haven't checked yet are the fusible links. I am assuming that you have to buy the complete wire containing this link since I don"t believe that they are serviceable. I am assuming that they should only show a fraction of an ohm if good, and an open circuit if bad, right? I will trace the voltage at the main fuel solenoid shortly. If it is as low as the shut-off solenoid...no wonder the engine won't start.

[DmaxMaverick]

You don't have to replace the entire wire harness if the link(s) are bad, at least temporarily. You can splice in a Maxi-Fuse of the correct amperage until you figure out what caused it to burn. Otherwise, you might buy more than one harness, because you don't know if you've fixed anything yet, and the next may burn like the first. Replacement fuses are a heck of a lot cheaper than a wire harness.

[JohnC]

Forget about measuring resistance. Put your negative probe on the battery negative connector. Set the meter to DC volts, 15 or more. Put the positive probe on the fuel solenoid fuse. Measure voltage with the key on. If it's good, move the probe down the circuit towards the solenoid. If it's bad, move up the circuit towards the battery. When the reading changes you've just moved past the problem.

You can make your own fuseable link, should that be the issue. Use a 2" piece of wire that is 4 AWG numbers greater than the wire you're trying to protect. E.G, if you're trying to protect a #8 wire, use #12 for the link.

[GMC-John]

From the start I was suspecting a wire problem around the fuel filter canister since it is so close to the main engine connectors. After testing the input connector directly at the DS4 (by the way, 4 pins show 5 volts and the other two open) I started moving around the main large connector at the middle of the firewall. I broke a couple of the grey clamps on this connector trying to figure out how to pry it open and still haven't opened it yet for cleaning. Anyway....the engine started quite easily. Robyn....you were right in suspecting wiring but the problem was actually farther toward the various loads than just the battery connections. Could somebody comment on how to open the main firewall connector?

[DmaxMaverick]

The firewall bulkhead connector is BOLTED together. Look for 1 or 2 bolts about in the middle ( # of bolts depends on year/model, I don't recall). They are often also glued around the edges with calking, so some persuasion may be needed to get it apart. The general rule is, unless you have an obvious, specific reason to disconnect it, don't. Unless you're repairing damage, it's better left alone. Absent obvious physical damage, the bulkhead connector is almost never an issue. Most all issues with it come after it's been messed with.

[Robyn]

Not sure we are all on the same page here.

Are you talking about the main engine connector that plugs to the engine harness ??????

The bolt together plug is more off to the drivers side of the engine bay.

The main feed from the ECM is located under the heater box and snakes up from below and ends up by the center of the firewall and then joins to the engine harness at the rear of the engine. (Actually lays in the valley at the rear of the engine)

A bad connection in one or more of the connections can certainly cause issues

Sadly when you have been fooling with wires and then things work it can be a pain to figure our which one was to blame.

I am with Maverick....the bolt together connector is not usually an issue UNLESS somebody been messing with it.

Here is a piccy of the engine harness....NOTE THE 3 PLUGS AT THE ONE END

These are the firewall end of the engine harness.

Any engine removal or such and these have likely been unplugged.

I would suspect these connectors before I would the main bulkhead connector.

Any one of the engine end (Multiple connections on the main harness) can make for issues.

Another connection is the power connection from the PMD harness that connects with the very rear lower end of the IP (Rubber boot there)

If anyone has messed with this AND THEY HAVE BY THIS LATE DATE.....Check the connections under the boot )

Now.....if you are fooling with a wire at the main bulkhead and things either stop or start....then by all means check it out.

An interesting story

Buddy of mine runs a local Diesel shop.

One day I stopped by for a couple minutes to BS at lunch time.

Guys are looking under the hood of a 97 Ford Power stroke.

"Wasssssup" I asked ?????

Answer "It just quits when the customer drives over the railroad tracks"

Engine is running happily away and I leaned on the RH inner fender where the Jack and tools are fastened down.

The engine quit......
EVERYBODY "WHAT DID YOU DO" ??????

A quick dig into the area found that the tire changing tools had not been replaced correctly at some time and the wiring harness had been worn through....a sharp bump would short things....

Some cleaning and tape up the wire harness plus adding some rubber shielding....

And getting the tools where they belonged.....Job done

Previous work and others thrashing about can result in all manners of trouble.

Anyplace that looks to have been messed with is suspect......

Good luck....

Keep us in the loop


Oh BTW

Electrical contact cleaner (Bomb can) dry connections and add dielectric grease to the connector pins before assembly.....

[GMC-John]

Your pictured connector harness is exactly the one that I am concerned about. The 6.5L troubleshooting guide refers to this large bundle as something that needs to be cleaned on occasion. How do you get this apart? Just keep pulling? I broke the grey plastic end cap on the top of mine.

[Robyn]

Great...... AT LEAST WE ARE ON THE RIGHT PAGE :):)

OK
On the side of the plugs are a locking tab....LIFT THE TAB.....I can't remember if there is a safety piece that keeps the tab locked.... Some plugs have a little plastic bar that slides through a hole in the tab to assure that it does not disconnect.


The larger plug has a slot on one side and the lock bar goes through the slot
If the locking bar ( BLUE, GRAY, RED ????) if its there needs to be carefully removed and then press the tab and slip the connections apart.

The slightly smaller plug has a tab on the firewall side that snaps over the engine plug.

Lift the tab and separate the plugs..

These plugs can not be mixed up......different sizes.




THESE ARE "OLD PLASTIC"...SPRING THE LOCK TAB JUST ENOUGH TO ALLOW THE PARTS TO SEPARATE...Warm weather is easier on these than cold.

These guys make a great replacement harness https://quadstartuning.com/products/6-5l-engine-wiring-harness

GM no longer supplies the harness...I found these folks back a while...good stuff.

The OEM lays in the valley and that is a nasty place for it.