Bidirectional 4L60E - solenoids

[D60]

I've got an '03 4L60E in a Silverado 1500/5.3 that is throwing nearly every solenoid code - P0740, 0753, 0758, and 0785. Maybe more if I drive it longer

IIRC it seems to have 2nd and 4th when I test drove it, or maybe it was 2nd and 3rd if that makes more sense...I forget how the solenoids work together for the various ratios.

Anyway it seems perhaps unlikely all these solenoids are bad at once? I'm of course wondering if we're looking at an electrical/wiring/grounding problem of some sort.

I should be capable of commanding the solenoids with my scanner so I was going to check at the plug at the transmission (which physically looks fine and seems to seat well, 13 pin if I counted right) to see if commands are getting that far.

First, I'm looking for switched GROUND, yes? Secondly, is it ok to command each solenoid with the key on, engine off I ASSume? Third, is it possible to damage anything if I command the wrong solenoids or [something]?

edit: I guess the last question is dumb 'cause the harness will be unplugged from the trans....duh

 

[clinebarger]

Does it have power? Classic symptoms of a bad ignition switch not powering Ignition 3 circuit. Ignition 3 fuses are marked as such in the I/P fuse box cover, Do they have power?

 

[D60]

Does it have power? Classic symptoms of a bad ignition switch not powering Ignition 3 circuit. Ignition 3 fuses are marked as such in the I/P fuse box cover, Do they have power?

Man I pulled the cover and I was SOOOO hopeful the crackhead wiring I discovered on what just happened to be the Ign 3 fuse was the culprit, but I removed it and no luck. It seems to seat tightly with the crackhead wiring removed (no idea what that powered). I really despise crackheads!

Anyway I found three fuses labeled as Ignition, specifically IGN 3, IGN 0 and TBC IGN 0 but they all have power on both sides.

I was able to look at Commanded Gear on my scanner and the trans seems only capable of recognizing 2 or 3. When it does shift -- presumably from 2 to 3 -- it's kind of harsh. It doesn't seem to recognize R on my scanner but Reverse works. I also don't get readings for P, N, D or 1 ...... only "2" or "3"

 

[D60]

If I clear codes and just run thru the gears on the shifter on the shop floor without moving an inch these are the first to appear. It will show "1" as commanded until it figures out something is wrong and trips the CEL, but I don't think it ever actually achieves First

 

[D60]

So I'm getting power at E where it should be. I'm able to command a ground for 1-2, 2-3, 3-2 and TCC. The TCC seems to time out after ~10 seconds...I'm gonna assume this is normal.

Is there an overall transmission ground I'm not addressing? I understand the solenoids are switched by ground so they don't need a constant ground....just thinking out loud.

Otherwise I'm beginning to think it's time to drop the pan and make sure the signals are passing through the internal harness, and if they are....new solenoids I guess?

 

[D60]

I don't wanna get in the weeds too much but this hot mess is over on what I'd call the MLPS. The crackhead kid apparently had a glass business and everything on the truck he managed to break (door panels, tailgate handle bezel, and apparently electrical connections) is "repaired" with urethane. It's ridiculous.

Anyway I don't think this is causing solenoid codes but if anyone thinks this could throw the codes I'm getting I'm all ears.

Again I don't wanna derail my own thread but want to mention anything potentially pertinent before I maybe buy solenoids (after tracing internal electrical)

 

[14Accent]

There's your first issue. The range switch is integral to your transmission working properly. Do yourself a favor: get the correct OEM pigtail connectors and rewire the range switch plugs. Also replace and align the range switch itself according to the factory procedure.

 

[paulo57509]

Yes, first replace the neutral safety/range sensor and the pigtails. GM uses some nasty sealer on the range sensor electrical connectors. Looks like someone used too much heat on the connectors when attempting to remove them.

The new switch/sensor should come with the proper alignment tool attached. OEM pigtails are available from RA.

I wouldn't dismiss an internal mechanical issue.

 

[clinebarger]

The Range/Neutral Safety Switch will not cause P0740, P0758, P0785 or abnormal transmission behavior, All that switch does is....Neutral Safety, Back-up Lamps, & the PRND321 display on the dash.

The potting from those Lucas made range switches flows into the connecters from Catalyst heat, GM didn't intentionally glue them in place.

It's odd to have more than 1 solenoid DTC & it not be a power issue, 4L60E Solenoids rarely fail to begin with. I think we need to start fresh so nothings looked over??

Let's test/concentrate on the Solenoid B circuit first....

*Remove the plastic shield covering the PCM, Unlatch the PCM & fish it up top for better access.
*Using a 7mm socket remove both PCM Connectors, The seals have a habit of sticking to the PCM.....Remove those & place them back into the Connectors.
*Remove PCM, Using a flash light....Verify none of the Pins have been pushed into the PCM from (The Dope Fiend) being careless.
*If that looks good....Check the Connectors for Pushed Out Terminals.
Displaced/Pushed Pins & Terminals are very common with P01 & P59 GM controllers!

If all that looks okay.....
*Remove the plastic cover over the C2 (Green) PCM Connector, Cut the little zip ties off if needed. Also blow all the dirt/debris out of the locking tab holes so the cover will release easier.
*Locate Pin 47, Yellow & Black wire (Solenoid B Control Circuit)
*Plug/Secure the 2 connector back to the PCM.
*Using a T-pin or a straightened Paper Clip to back probe right beside the Solenoid B Control Circuit down into the connector & make contact with the Pin/Terminal.
*Using a Volt Meter hooked to ground.....Key on....You should have close to Battery Voltage, Command Solenoid B on & the voltage should drop to Zero.
*If you have NO voltage return at the Solenoid B Control Circuit at the PCM..... Use a Incandescent Test Light hooked to Battery +, A short to ground will cause the light to illuminate.
*If the circuit is not shorted to ground......Back Probe Pin B (Yellow & Black wire) at the Trans Plug.
*If you now have Voltage Return.....The Solenoid B Control Circuit between the Trans & PCM is open.
*If still no Voltage Return.....The Issue is in the Internal Harness or the Solenoid itself. (Solenoid could be unplugged?)

P0740 get's diagnosed the same way, Except you'll be on Pin 42 of the C2 PCM Connector & Pin T of the Trans Connector (Tan & Black wire).

EDIT......P0740 is not a valid DTC for 2003-2007 GMT800 trucks!!
You may be working on a 2002??, That's Okay as the only change in the diag is the C2 PCM Connector color is Red not Green....Everything else is the same.

Another EDIT.....Check the Trans Connector for Pushed Pins/Terminals....Not as common because it's a lot harder to seat/force the connector in by hand vs having a hold down bolt easily force pins/terminal out of place.

 

[D60]

Thank you @clinebarger , I'll get after it in the next day or two. I was also very skeptical the range switch would cause this.

It's definitely an '03..."angry eyes" headlights, updated '03+ cluster complete with almost-failing PRNDL display, red rear turn signals,, push/pull pw switches vs push/push rockers. Also the i/p fuse labeling speaks of SEO and I thought the addition of SEO came with the '03 electrical update.

I was almost wondering if the PCM had been swapped at some time because the truck has crazy high miles but the VIN called up on my scanner matches the dash placard.

The weird thing to me is the truck reads 402k on the odo but the driver's seat bolster isn't broken down and the interior overall doesn't match 402k. Similarly the engine bay is surprisingly clean and there are minimal oil leaks from engine or trans. Maybe just the cluster was swapped out at some point...with trucks like this everything is a mystery.

 

[clinebarger]

Did some more checking.....P0740 is indeed a valid DTC for this 2003, Alldata Pro which I pay @ $2,400 a year for didn't list a P0740 for a C1500 Silverado, But a 2003 Suburban does.
Checked the master DTC list on a 2003 tune file via HP-Tuners....Also shows P0740.

 

[D60]

Ok, finally getting back to this. Visually all checks out, I carefully inspected with headlamp and a flashlight for pushed-in pins or connectors, but nothing.

You were dead right about the seals staying on the PCM!

Now, on Pin 47 I do get batt voltage. Drops to 0.2V (I'm going to assume this is "zero") when I engage 2-3 shift solenoid but does time out eventually returning to batt voltage.

On Pin 42 I do also get batt voltage. It drops to ~7.4-8.6 when I engage "TCC control solenoid" and then times out, returning to batt voltage after a few seconds. HOWEVER I then tried "TCC enable" on my Xtool and it drops to 0.15V, again timing out.

I think the issue above is terminology/language barriers in inexpensive scanners

 

[clinebarger]

The next technical step is too Ohm the Solenoids, Which I absolutely hate. Amperage measurements on BOTH shift solenoids would be a more accurate testing method as there's two identical Solenoids & only one is setting a DTC.

My gut feeling is a PCM issue. There are dedicated "Sensing" circuits for the voltage rationality....meaning you can have false DTC's as the Solenoid Driver (Base Transistor) is sound but the Sensing/Diagnostic Circuit is damaged.

I have unlimited HP-Tuner credits for all GMT-800's....I'd simply turn the DTC's off & test drive the vehicle. Advise the customer that the PCM is damaged & cloning a good used one is X amount.

 

[D60]

Thank you @clinebarger

Just so I'm clear, is it your belief if the solenoids are ok then disabling DTC's would allow it to function normally?

edit: it's not important but to be clear in what I mentioned in Post #12 about terminology, I'm ASSuming the varying TCC voltage i was seeing was a result of TCC PWM but the Xtool menu seems a bit vague. Maybe this is standard, though. Either way, it doesn't matter

 

[clinebarger]

You got it!!

Pin 42 is the TCC Enable Solenoid & IS NOT PWM controlled, The TCC PWM Solenoid is on Pin 2 of the C2 connector. Not sure why you would get seemingly PWM average voltages on Pin 42.
*If these circuits were shorted together....A P2761 DTC should be generated for TCC PWM Solenoid electrical fault along with the P0740.

For now I'll chalk this up to generic scan tool anomalies. But would certainly keep this in mind during a test drive (After deleting the DTC's).....
*Have data PIDs.....TCC Slip RPM, TCC Enable, & TCC PWM duty cycle where they can be monitored at the same time.
*TCC Enable should switch to YES.....But the TCC Slip RPM will remain steady because TCC Apply Oil is still being dumped by the TCC PWM Solenoid via the TCC Regulator Valve.
*When the TCC PWM duty cycle starts to rise or drop (Some scan tools display this PID inverse of others).....About 40% or 60% duty cycle.....The TCC Slip RPM should be near Zero.
(Depending on wear in the TCC Regulator Valve Bore......Full TCC lock can require greater/lesser duty cycle.

If the TCC full locks when the TCC Enable PID switches to YES.....There's a wiring issue or the PCM is really FUBAR'ed.

I like to keep things simple, Which is why I would concentrate on the 2-3/B Solenoid Circuit & the Solenoid itself because 1-2/A Solenoid Circuit & Solenoid are identical except the PCM pin they're terminated to......Same resistance & amperage signature.

 

[D60]

The next technical step is too Ohm the Solenoids, Which I absolutely hate. Amperage measurements on BOTH shift solenoids would be a more accurate testing method as there's two identical Solenoids & only one is setting a DTC.

My gut feeling is a PCM issue. There are dedicated "Sensing" circuits for the voltage rationality....meaning you can have false DTC's as the Solenoid Driver (Base Transistor) is sound but the Sensing/Diagnostic Circuit is damaged.

I have unlimited HP-Tuner credits for all GMT-800's....I'd simply turn the DTC's off & test drive the vehicle. Advise the customer that the PCM is damaged & cloning a good used one is X amount.

Ok finally returning to this issue. I know it's a bit parts cannon-esque but I replaced the A,B and 3/2 downshift solenoids. Given the cost it wasn't a big deal.

This also gave me an opportunity to probe each respective solenoid connector inside the pan and each had a constant hot and a switched ground when commanded.

Sadly - but as expected - the problem remains. On my short ~6 mile test drive I did get only a P0758 for solenoid B. It sure seems the trans achieves at least 1,2 and 3 until it decides there's a problem....then I seem to have 2 and a reluctant 3. It's definitely not locking the converter even at highway speeds.

Anyway, @clinebarger you've got a PM coming