Range Shift Inhibited, EBCM failure?

tpijeep

New member
Oct 20, 2009
26
0
0
Ruston, LA
I am having multiple issues with my 03 Dmax and I am thinking they are all pointing to the same thing but I don't know what that may be.

Background, put a PPE stage 5 kit in tranny 2 years ago, has worked perfectly, running a DSP5 tune from Duramax Tuners

About 4 months ago I got a Service Brake System warning on the display which cleared up as soon as I got out of the driveway, I ignored it. They a started seeing random characters on the dash display which were intermittent. Then sometimes the Dash would not work at all, turn off restart and all would be well. These were annoying but didn't seem to be a big issue.

THEN, pulled away from stop sign and I had a hard shift from either 1-2 or 2-3, wasn't paying attention, REAL Hard. I noticed several harder then normal shifts so i did a trans relearn from my CTS and gave it a day or so to relearn.

From this point forward the tranny has been acting crazy, you never know when your going to get a hard shift, or HARD downshifts, harsh TC engagement or if its gonna work perfectly normal. Fluid looks fine, gonna pull spin off here shortly and check for metal.

I ran the codes and I have a bunch of them yet doing online research they seem to be connected. Here they are

P0100 Mass Air Flow Sensor Circuit
P0400 EGR System
P0380 Glow Plug Feedback Circuit A
P1626 Theft deterrent Start/fuel Enable signal lost
U1152 Lost comm with HVAC control
U1041 Lost Comm with Brake/Traction Control
U1003 ???
C0035 LF wheel Sensor
C0040 RF Wheel Sensor
C0055 Rear Wheel Sensors
C0245 Wheel Sensor Frequency Error
B1440 Power Mode Master Input Circuits Mismatch
B2610 Passenger Compartment Dimming (single or ...
U1000 Class 2 Data Link
U1305 Class 2 Data link high or low
U1301 Class 2 Data link High

Any clue of these point to a common issue? I have read rough downshifts can relate to ABS sensors.

I changed the ignition switch and Neutral Safety switch, didn't help, reground EBCM ground and added large grounds to both the body and frame.

I have had an intermittant problem where the dash would be dead and I sharp hit on the dash board would make it light up, this is still occuring.

I added another ground wire to the body, I checked all the grounds on the Pass side of engine, checked for chaffing all around the transfer case and up both wheel wells and around the PS pump.

We unplugged the EBCM and those connectors are fine, traced back to the fuse block all good.

We did a system check, still Range Shift Inhibited no dash lights or MIL

Started digging around the connector block behind the Ebrake pedal (the one the aftermarket brake control plugs into) and the ABS and BRAKE lights lit up. Checked codes and the EBCM is no longer being reconized by my EFI Live.

Checked all the connectors on the BCM, checked the Transfer Case module, found a little corroision on a few pins, cleaned them up and reinstalled.

Still EBCM not present?

All fingers point to EBCM, why would it just go away?

Checked power at the EBCM and it was good, Yet the EFI Live will not recognize that its there.

If I tow it down the road it will get up to speed 2nd gear works fine and will hold 2nd until you shift it to neutral. Pulled and cut the spin on filter and there are no large particles in it, just a fine metal dust on the filter magnet.


I am sorry this post i so chopped up, I had it on another forum and got no responses so I cut and pasted here hoping for some assistance!

Thanks!
 

onebaddmaxxx

Active member
Feb 22, 2009
1,212
1
38
Cecil County Md
I would start with changing the rear wheel speed sensor in the transfer case. c0055 is a speed malfunction. The ally will flip out and act stupid without that sensor working correctly. Check and make sure the wires arent brittle as well.
 

tpijeep

New member
Oct 20, 2009
26
0
0
Ruston, LA
I just put the truck up on my lift, The Speed sensor is clean and wires are in good condition. I put it in gear and my CTS tuner indicated a 2nd gear request and I could run it up to 40mph but it would never request 3rd. If the Speedometer is working wouldn't that indicate the rear VSS is operable?

I ran the codes again and the TCM is throwing a P0746 (Pressure Control Sol A Stuck off)and P0731 (Incorrect 1st gear Ratio)

These point to clutch failure but I had no indications of this before I checked and cleared the codes. I still have no COMM with EBCM module, it doesn't even come up on list of modules with EFI Live and my ABS/Brake light still illuminated.

I hate to crack the tranny until I hunt down the gremlin, I also got a P1500 Start Switch Circuit which I can find no information on.

:confused:
 

jc1843

New member
Sep 27, 2009
228
0
0
86
So Calf
With those codes, I suggest you start with a new ignition switch. Easy 10 minutes-- pull the lower steering column cover-- the switch is only held in with plastic clips. Just pull it down. Have the key part to "ON", when you insert the new switch- then it should be indexed correctly.
 

DAVe3283

Heavy & Slow
Sep 3, 2009
3,733
305
83
Boise, ID, USA
All the U1xxx codes indicate Class 2 data bus communication failure, which is usually caused by damaged wires. The reason the ABS light is on is your dash can't communicate with the EBCM (just like EFI).

Since you swapped a new one in, and it didn't come to life, you now know the problem is not the EBCM itself. You need to go over the harness with a fine tooth comb and find the broken/shorted wire(s). Not what you wanted to hear. This probably means pulling the wires out of the loom. Focus on the Class 2 and CAN bus wires, those are the ones we know have issues.

This would not be the first time one or two wires went bad / got damaged inside a harness while the rest were fine. An errant rock off the bottom of the truck can do damage but leave little trace.
 

DAVe3283

Heavy & Slow
Sep 3, 2009
3,733
305
83
Boise, ID, USA
These should help.

The twisted pairs are the ABS sensors on the front wheels. The Class 2 is a single wire. See the attached schematics and connector pinouts.
 

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