I have a B1M00229 articulated truck that has issues with the trans. Error codes are always active for trans speed sensors 1&2, (585-2 and 683-2 data erratic, intermittent or incorrect ) and truck will drive in reverse well, but will not move forward. New sensors have been installed, and continuity of wires to pins at Trans controller ECM has been checked. What can I be misssing?
I'm assuming you mean 673-2 not 683-2.? Try the attached troubleshooting procedures.
Thanks, we did test resistance on the twisted sets for each sensor at the ecm plug with the sensors hooked up and compared to the good sensors, seemed to be fine but well will recheck with the jumper wire
I don't recommend a resistance/continuity test as a good measure of wiring integrity despite the fact that's what the troubleshooting procedure say. Why.? Because if you have a wire somewhere "hanging by a thread" it can show continuity when measured with a multimeter, but passing any sort of current is beyond its capabilities. In your case I would prefer installing a jumper at the sensor plug, then at the ECM end of the two wires jumper one to machine frame ground and use a 5A test light powered from batt+ on the other. If the wire pair will pass 5A then I would call the continuity good.
Understood, bad contact can be a deceiving one. Im making up a jumper plug shortly and headed back out there. In my mind, why would it move in reverse, with no sensor input, and it won’t even go into 1st gear forward. I realize the speed sensors are key to sequential shifts, but being “Hall effect” type sensors, nothing would register anyway without movement. I’m just having a bit a hard time wrapping my mind about the design side. Thought I’d get movement in gear one, maybe not an up shift. What can the powertrain controller see form a stagnant Hall effect sensor?
Have you been focusing on chasing the sensor codes or did you also take a look at the transmission oil, filter, & suction screen condition.? Have you tried a transmission clutch calibration.? Any recent welding work done on the truck.?
The codes will be active if the transmission is slipping or not engaging. It's probably not a sensor problem but a trans. Clutch problem. May be as simple as modulation valves sticking.
Just finished with the jumper wire/test light. Fed one side and lit the light on the othe. Checked for continuity to ground, none. Both circuits tested same way. I’m pretty confident the wiring is ok. The truck was parked last Thursday night operating normally. Friday am was cold and the guys did boost it. I have my concerns on that, but none the less have to find the issue. It did back up from its spot, moved forward probably 250 feet and stopped with amber trans light and horn. I came Saturday with a pickup and ET and pulled these codes. I had no tools to tilt cab or anything so shot from the hip and grabbed output speed sensors for the return trip. After the sensor install and no improvement, I did the continuity of the 15-16 and 17-18 wires at controller(might have the numbers off, I don’t have my worksheet right now) but the pins that are for those twisted pairs. The resistance was basically the same as the new sensor before install, so I took that as a good circuit. Same results today. Oil level was confirmed, but no filters or screen has been checked right now, but I did do a full trans service back at the shop no more than about 50 hrs ago with nothing Suspicious found, just routine. If it’s dropping oils like that etc.. might be lowbed time, these sites aren’t that easy for that work anymore. I’m the owner of the truck, and mechanic from years back, but I’ll admit I’m rusty lol. It goes into gear quickly and positively in reverse, no pressure alerts or anything, with output speed codes present. I’m still wondering if a working truck would go into a forward gear without speed sensors or not. Codes for speed sensors stay active whether it’s in gear or not. I still wondering what the controller expects to see from a non moving collapsing field sensor. Seems to me if an internal piston or something was blown out, a pressure drop alert would result? Looks like lots of reading tonight.
It will go into gear even with the active code. I doubt it’s a blown piston seal but rather a control valve issue. If it was sitting out in this super cold weather we had it could create all kinds of control issues especially if the filter was bypassing on startup.