Ryanp Posted February 10, 2022 Share Posted February 10, 2022 Hello everyone, I have a 2004 MR688 that I just got running this week. It has sat for probably 4 years, in the sun I might add. It has an Allison HD4560P transmission that is spitting out a bunch of codes and refuses to go into gear. Before I got it up and running I drained the oil. Probably only had 2 gallons in it. Then changed the filters. I believe I put about 4 gallons of fluid in it so far and I haven't checked yet to see how close it is but it shouldn't be too far off. Anyway the codes on it are 1412-oil level sensor failed low 2314-secondary shift selector fault 3312-sump oil temp sensor failed low 4522-G curcuit solenoid open 5587-oncoming c3ps test N1 to reverse and possibly 4523- solenoid H I see two of them might go away if I top it off more but I was wondering if there is a way to test the harness to diagnose these things. The harness is baked and cracked laying across the trans so that's highly suspect. Thanks Quote Link to comment https://www.bigmacktrucks.com/topic/69187-2004-mr688-transmission-problems/ Share on other sites More sharing options...
JoeH Posted February 10, 2022 Share Posted February 10, 2022 I think it takes like 42 quarts, probably including torque converter. Oil level should be high on the dipstick, normally you check trans levels when they're warmed up and running. Quote Link to comment https://www.bigmacktrucks.com/topic/69187-2004-mr688-transmission-problems/#findComment-489030 Share on other sites More sharing options...
JoeH Posted February 10, 2022 Share Posted February 10, 2022 Secondary shift selector would be for an LE688 with secondary controls in the passenger side. (Steering wheel, brake & accelerator pedal, secondary shifter pad...) Quote Link to comment https://www.bigmacktrucks.com/topic/69187-2004-mr688-transmission-problems/#findComment-489031 Share on other sites More sharing options...
JoeH Posted February 10, 2022 Share Posted February 10, 2022 Quick Google search comes up with way more than 4 gallons. Closer to 9 gallons. Remember, the trans fluid does a ton of work, it's not just lubrication. It's the hydraulic oil for shifting gears, operating the torque converter, etc. Builds a ton of heat and takes a lot of abuse. Quote Link to comment https://www.bigmacktrucks.com/topic/69187-2004-mr688-transmission-problems/#findComment-489032 Share on other sites More sharing options...
Ryanp Posted February 10, 2022 Author Share Posted February 10, 2022 Well I thought I had the fluid close but it sounds like I'm only half way there. Thanks for clearing up the secondary controls thing. I will grab another pail at napa and see what goes on. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/69187-2004-mr688-transmission-problems/#findComment-489050 Share on other sites More sharing options...
Vmac3 Posted February 11, 2022 Share Posted February 11, 2022 May want to check for rodents that may have found a place to live in or on the truck someplace. I had an LE with a rats nest inside the center console and that they chewed their way through and made a comfy home for themselves. V 1 Quote Link to comment https://www.bigmacktrucks.com/topic/69187-2004-mr688-transmission-problems/#findComment-489146 Share on other sites More sharing options...
Joey Mack Posted February 11, 2022 Share Posted February 11, 2022 so true 'V'... Glad to see you again... missed you... Jojo 1 Quote Link to comment https://www.bigmacktrucks.com/topic/69187-2004-mr688-transmission-problems/#findComment-489177 Share on other sites More sharing options...
Ryanp Posted February 12, 2022 Author Share Posted February 12, 2022 Well I put another 7 gallons in so I was way lower than I thought I was. After that it shifted into gear properly and all seemed well. Decided to take it for a lap around the shop and when its about ready to shift into second gear the indicator goes from 5 (normal) to 1. Clicking the up and down arrows didn't change anything. Then when I got it back to the shop to pull in I had to shut it off and disconnected the batteries because the shifter wouldn't go to neutral. Upon restart it will do forward and reverse like normal but if I drive it far enough for it to want to shift I will get stuck in 1st again. Its possible I have a bad sensor or 2, a couple of bad wires, or even the wires hooked to the wrong sensors on the trans. I've looked online and haven't turned up a good picture showing what sensor does what. I believe there are 3 on the passenger side and then the speed sensor on the output housing. I do have schematics with wire numbers saying what sensors they go to but they don't show the locations of the sensors. Also I'm still getting the 2314 code for the secondary shift selector. All my other codes cleared out other than this. Why would that be? There was a 4-1 blink code for the speed sensor but I think it went away. Thanks, Ryan Quote Link to comment https://www.bigmacktrucks.com/topic/69187-2004-mr688-transmission-problems/#findComment-489185 Share on other sites More sharing options...
JoeH Posted February 12, 2022 Share Posted February 12, 2022 I think you indicated this truck was put together from 3 trucks? If so, maybe the transmission came out of an LE with secondary controls? Secondary control feature could be turned "on" in one of the computers? Just a guess. You could have wires plugged into the wrong sensors. Going off my memory from having just played with my transmission last week there are 3 sensors along the pass side in one harness and a 4th plug coming off the Mack harness going down to one of the trans oil cooler lines below the tail shaft. The 3 plug harness gets plugged in "rear to front" meaning the very last plug on the harness goes in the front most sensor, then the other 2 I think come out of close to the same spot on the harness but one is longer than the other. The longer of those 2 goes to the middle sensor and the shortest pigtail goes to the rearmost sensor. Beyond that all I can guess is the trans needs to get rebuilt? Really don't think I know much more than this ... Quote Link to comment https://www.bigmacktrucks.com/topic/69187-2004-mr688-transmission-problems/#findComment-489191 Share on other sites More sharing options...
JoeH Posted February 13, 2022 Share Posted February 13, 2022 Any change in what codes are present? Quote Link to comment https://www.bigmacktrucks.com/topic/69187-2004-mr688-transmission-problems/#findComment-489284 Share on other sites More sharing options...
Ryanp Posted February 14, 2022 Author Share Posted February 14, 2022 Ok, so my latest on the truck is I got it driving this afternoon. I took out the trans sensors and cleaned/ inspected them. Looked good so back in they went. Took my blue connector off the trans ECM as per my schematic, jumped the sensor plugs and tested continuity at the ecm pins to see if It made a loop. Engine speed sensor and turbine sensor wires tested out good. Output sensor failed loop test. Messed around for a while and found the problem was between the hinge point connection and the sensor plug. Here's the weird part- I rolled back the loom at the hinge point connection, and where my wires were supposed to be pinned in at they were pinned in but only ran 4" and had what looked like factory sealed wire butt ends? Schematic said that the wires didn't run to anything special from there just back to the sensor so I ran a new set of twisted wires and plugged it all back in and it tested right and passed the road test. My question is where did the wires go that were leading from the sensor forward in the harness?? Possibly to the speedometer because that's not working now. Not sure if it was before or not. Current trans codes are 2314 and 2511 Still have a 1-4 and 4-1 on the blink codes. I haven't tried resetting the trans codes yet and I'm not sure how to on the blink codes? Thanks for all the help, it was fun driving down the road before dark even if it was 10 degrees out. Quote Link to comment https://www.bigmacktrucks.com/topic/69187-2004-mr688-transmission-problems/#findComment-489359 Share on other sites More sharing options...
Joey Mack Posted February 14, 2022 Share Posted February 14, 2022 1-4 should be ambient air temp 4-1 should be vss, speed sensor in the tranny output shaft.. correct me if i'm wrong... jojo Quote Link to comment https://www.bigmacktrucks.com/topic/69187-2004-mr688-transmission-problems/#findComment-489361 Share on other sites More sharing options...
JoeH Posted February 14, 2022 Share Posted February 14, 2022 On mine, the ambient air temp sensor is on the driver side in the grill, near where the trans "clean power" wires go into the harness. Your VSS should clear up when you figure out what's going on with your speedometer.... Quote Link to comment https://www.bigmacktrucks.com/topic/69187-2004-mr688-transmission-problems/#findComment-489378 Share on other sites More sharing options...
Vmac3 Posted February 16, 2022 Share Posted February 16, 2022 On 2/11/2022 at 6:41 PM, Joey Mack said: so true 'V'... Glad to see you again... missed you... Jojo I appreciate it. V Quote Link to comment https://www.bigmacktrucks.com/topic/69187-2004-mr688-transmission-problems/#findComment-489518 Share on other sites More sharing options...
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