Stuck but in safe area. Trans retarder & speedo not working,low engine power

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Stuck but in safe area. Trans retarder & speedo not working,low engine power

July 19, 2020, 06:57:12 pm

After 4 hour driving with no problems, the trans retarder is not working, the speedometer is not working and the engine revs fine but does not give much power. The cruise control may also not be working because after turning it on while in idle, hitting RES does not put engine in fast idle.

Trans fluid is OK, engine and trans not running hot. No fluid leaks, and no obvious air leaks in CAC.

Engine starts OK and sounds normal at idle. Stop engine slow flashes when turn key to first position but goes out after starting engine. Check engine goes on after starting engine.

All ideas appreciated. I'm about 15 miles from a Cummins dealer in Dedham Mass south of Boston.

2004 Cummins ISL

Re: Stuck but in safe area. Trans retarder & speedo not working,low engine power

Reply #1 – July 19, 2020, 07:06:31 pm

Did have low voltage on the dash?
If so close your boost switch and see if tying the battery systems together helps.

Mike

Re: Stuck but in safe area. Trans retarder & speedo not working,low engine power

Reply #2 – July 19, 2020, 07:09:38 pm

Could the fuel filters be starting to plug up, when was last change or low on fuel in tank.

Re: Stuck but in safe area. Trans retarder & speedo not working,low engine power

Reply #3 – July 19, 2020, 07:11:47 pm

Yup, what is voltage on the dash gauge??? THAT is where to start, since you don't even have to leave the driver's seat.

If below 13.0 with engine running, where are some EASY work-arounds that will get you where you want to go-- also from the driver's seat.

Re: Stuck but in safe area. Trans retarder & speedo not working,low engine power

Reply #4 – July 19, 2020, 07:18:04 pm

13.8v on engine bats when running

Don't think it's a fuel problem but I can check the water separator. Less than 2,000 miles since filter changed. I have a spare filter on board.

Re: Stuck but in safe area. Trans retarder & speedo not working,low engine power

Reply #5 – July 19, 2020, 07:44:51 pm

I had a similar problem last year and it turned out to be the battery isolator. My workaround was To run generator with boost switch on to keep both sides charging.

Re: Stuck but in safe area. Trans retarder & speedo not working,low engine power

Reply #6 – July 19, 2020, 07:46:35 pm

Quote from: pibutler – July 19, 2020, 07:44:51 pm

I had a similar problem last year and it turned out to be the battery isolator. My workaround was To run generator with boost switch on to keep both sides charging.

But, if voltage is 13.8, there is no alternator isolator or charge wiring issue.

Indeed, your is one of the "go to" work arounds with a failed alternator or isolator.

Re: Stuck but in safe area. Trans retarder & speedo not working,low engine power

Reply #7 – July 19, 2020, 08:12:35 pm

Agree, in my case everything was normal at first with 13.8 to 14.3 measured at alternator and measuring both sides of isolator, and then as my isolator would heat up it would fail intermittently for sometime 30 minutes. It took the tech several hours to get the isolator to replicate the issue. He called it "gremlins" were hard at work trying to trick him.

Re: Stuck but in safe area. Trans retarder & speedo not working,low engine power

Reply #8 – July 19, 2020, 08:24:22 pm

I changed both fuel filters. The one with the plastic bowl was gummed up. I didn't want to use the fuel from the old filters in the new ones.

How long does it take crank the engine to get fuel into the new filters and start the engine?

Re: Stuck but in safe area. Trans retarder & speedo not working,low engine power

Reply #9 – July 19, 2020, 08:39:23 pm

Probably if you turn on your key leave it for 15 second then turn the key off and keep doing doing that key on 15 seconds then off
for 6 times then try to start it. If it doesn't start do the on off some more. It should bleed itself. The timing of how long to leave
the key on I'm not sure as when I had and 8.3 I had a primer switch in the back and it would bleed the filters.

Re: Stuck but in safe area. Trans retarder & speedo not working,low engine power

Reply #10 – July 19, 2020, 09:54:07 pm

Still have problems after changing fuel filters and getting engine started. Now trans shows a "1" on the selector display after putting in drive and going a short distance. Is that a "limp home" mode?

Re: Stuck but in safe area. Trans retarder & speedo not working,low engine power

Reply #11 – July 19, 2020, 10:10:35 pm

Checked Trans diagnostic codes. Got 2511 Output speed sensor at 0 in 1st and 2216 output speed sensor.

Re: UPDATE Stuck. Trans retarder & speedo not working,low engine power

Reply #12 – July 20, 2020, 12:47:22 pm

UPDATE - I checked the speed sensor for continuity. It's a magnet and should be about 300 ohms at 70 degrees. VOM shows it as open - no continuity. An Allison service shop said they do go bad but not frequently.

I tried to remove it, its held in via a clip with 1/2" bolt (not shown in the picture). I got it loose but the flywheel/balancer (large round metal piece at the drive shaft end- please tell me what's it called) is too close to pull it out.

Short of removing the flywheel, are there any other ideas on how to remove the sensor? I could of course break the sensor to get it out but I still wouldn't be able to get the new one in.

Allison shop is about 30 minutes away. I will have to get the RV towed since with the bad sensor, the trans stays in first gear.

SEE NEXT POST for picture

Re: Stuck but in safe area. Trans retarder & speedo not working,low engine power

Reply #13 – July 20, 2020, 12:52:11 pm

Re: Stuck but in safe area. Trans retarder & speedo not working,low engine power

Reply #14 – July 20, 2020, 01:24:41 pm

Larry,

I hate to say this but you need about 1/4" more room for that sensor to come out past the harmonic balancer. Never had any luck with a pry bar trying to make more room. You would have thought they would have an access place that you could index the driveshaft to so you could remove that sensor with out a lot of trouble.

Mike

Re: Stuck but in safe area. Trans retarder & speedo not working,low engine power

Reply #15 – July 20, 2020, 01:27:57 pm

Just for the heck of it try to clean the contacts some how, will a pencil eraser fit, then spray with WD-40,nothing to lose,or what about somehow cutting some platic away from the sensor.

Re: Stuck but in safe area. Trans retarder & speedo not working,low engine power

Reply #16 – July 20, 2020, 01:29:11 pm

Any chance there's a notch on the balancer you could rotate to?

Re: Stuck but in safe area. Trans retarder & speedo not working,low engine power

Reply #17 – July 20, 2020, 06:30:30 pm

I would call that a U joint yoke. To get it off you need to take the U joint apart and then there should be a nut that has to come
off and then the yoke should pull out. Look and see it there is a place on the yoke that is indented for the sensor to come out.

Re: Stuck but in safe area. Trans retarder & speedo not working,low engine power

Reply #18 – July 20, 2020, 08:31:01 pm

Make marks on the flange 180 apart.
Die grind a tiny bit of clearance on one mark until the. Sensor clears.
Die grind the same amount from the other side.
It looks like an angle and not a huge amount of metal.

Re: Stuck but in safe area. Trans retarder & speedo not working,low engine power

Reply #19 – July 20, 2020, 08:54:39 pm

I would use Mikes suggestion before having to remove the damper to change it. Plus side it can be changed out again easily. Just hope it isn't so long it hits the main part of the damper. Can you get a measurement of a new one to verify?

Re: Stuck but in safe area. Trans retarder & speedo not working,low engine power

Reply #20 – July 20, 2020, 09:38:31 pm

Update: Thanks for all the ideas.

With a lot of study of the design of the sensor, I was able to use my dremel to shave off about 1/4 inch of plastic on one side of a ridge that is around the sensor and that allowed it to be removed.

Then I picked up a new one that also required some creativity to fit. Allyson part #29544139, Sensor Assembly-Speed, Rotational. It's an assembly because it includes a metal clip that is in turn held by a bolt. ($100+). I had to flip the clip around 180 degrees so the wiring connector could fit. Also it has a different cross section and its connector end is straight vertical instead of being at a right angle like the original. I got it installed but the wiring connection end is about 1/8 inch from the balancer. That's the good news.

The bad news is that it didn't fix the problem. At first I thought it did because the diagnostic code, 2511, cleared. But as soon as I started to drive, it showed again and the trans was limited to first gear. Note then when this happens, you can't shift into reverse or even neutral.

The plan is to get towed to the shop tomorrow. The service manager told me they disconnect the wiring harness from the control unit and plug in their tool which checks each sensor and the wires.

Hopefully the problem is a simple bad wire. I could work on it but after a day and a half in the sun in a grocery store parking lot, I'd like to get this behind me.

"When you're up to your bum in alligators, it's hard to remember your original intention was to drain the swamp."

Re: Stuck but in safe area. Trans retarder & speedo not working,low engine power

Reply #21 – July 22, 2020, 10:22:49 am

In for trans service. Anyone know where the Transmission Control Unit is mounted? Near engine or under trans gear selector?

It should be a silvery box.

Re: Stuck but in safe area. Trans retarder & speedo not working,low engine power

Reply #22 – July 22, 2020, 11:03:00 am

Larry,

Seems like on those year coaches they moved them from under the dash to the basement. Look around the HWH boxes in that same area.

Mike

Re: Stuck but in safe area. Trans retarder & speedo not working,low engine power

Reply #23 – July 22, 2020, 11:04:13 am

In our coach (which is build number 10 away from yours), the transmission control is in the compartment with the inverter and HWH controls.

Re: Stuck but in safe area. Trans retarder & speedo not working,low engine power

Reply #24 – July 22, 2020, 02:57:52 pm

Thanks for the fast response.

They agreed with what I figured out that it's a bad speed sensor - they tested and confirmed the part is bad. So if you get diagnostic code 2511 on the trans, the speedometer and the retarder stop working, the speed sensor may be the first thing to check. It should read around 300 ohms at 70 degrees.

The new sensor that I got from them, however isn't the right one. There is a specific sensor (I'll get the part number) that is required for a trans with the retarder. They said it's longer than the standard one.

Should have the part tomorrow and then will see if it can be installed without removing the balancer.

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