Transmission temp gauge

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Transmission temp gauge

July 17, 2015, 04:30:19 pm

Let the questions begin. When I test drove the rig I noticed that the transmission temp gauge wasn't working. The PO said that it was working when he drove it from Wichita then it stopped. I would suspect a possible loose wire or ground. Where /what am I looking for?

Larry

Re: Transmission temp gauge

Reply #1 – July 17, 2015, 07:12:51 pm

Larry,

On your coach you should have a couple of hoses that come out of the end of the transmission. (these are to the front of the coach) on one there is a sending unit. This sending unit feeds the dash gage. If you pull the wire off the sending unit the gage should go wide open. (to do this the ignition switch must be in the run position) If this happens take some contact cleaner and clean the grease off of this connection. If the gage don't move then a new gage is in order. The grease comes out of the U joint that is located just above of this connection. Here are a couple of pics. of what you are looking for even though they aren't too good hopefully you can make the sending unit out.

Pamela & Mike

Re: Transmission temp gauge

Reply #2 – July 17, 2015, 07:13:22 pm

The transmission temperature gauge hardly ever moves on our coach. The temperature will come up if I use the retarder while traveling down a long hill. Even going down a long grade while using the retarder, I seldom see a temperature over 230F.

Your gauge may be functional, but you've not done anything to raise the temperature enough to show a change.

We drive at 65MPH on good flat open road. We travel down grades at about the same speed that the coach can maintain going up the grade. That often means selecting 4th gear and traveling at 45 mph on a downhill.

Re: Transmission temp gauge

Reply #3 – July 17, 2015, 07:48:33 pm

My silver leaf showed the temp on the transmission going from 168 to 193 and the gauge did not really move. When it breaks 200 it starts to show on the gauge. One of the big reasons I went to the Silverleaf. I rarely look at the dash anymore other then the mechanical air gauges I put in.

Re: Transmission temp gauge

Reply #4 – July 18, 2015, 01:38:15 am

Doesn't your coach coach have electronic controls? If so, VMSPC would be a great addition and backup to the analog gauges...

Don

Re: Transmission temp gauge

Reply #5 – July 18, 2015, 06:48:46 am

Pamela and Mike, I will look under the coach and find the wires as soon as I get the safety stands. Where I'm parked at now, the rear of the coach is at full height to be level, but I don't want to take a chance to be a statistic.

J.D., my gauge never moved from below 90. The air is warmer than that 😕

John and Don, I am not sure if it is electronic or not. How can I tell? I see a gray plug right under the air brake that looks like a diagnostic plug. Between the heat, rain, Internet, TV and moving in, my poking and prodding have been limited. Oh yeah, I retired a couple of weeks ago, so now I have time

In my limited time of looking, I have found some unknown buttons and switches which I am saving for future questions.

Thanks again for all the help. Keep the suggestions coming.

Larry

Re: Transmission temp gauge

Reply #6 – July 18, 2015, 06:57:22 am

Dave,

Am I correct that there is a different set of temperature wires then for the retarder? If the retarder gets warmer, will it raise the temperature on the tranny? I don't want to inadvertently do any damage, so if I can get VMS for the coach, its another thing to add to the list.

Thanks, Larry

Re: Transmission temp gauge

Reply #7 – July 18, 2015, 07:44:12 am

Quote from: ohsonew – July 18, 2015, 06:57:22 am

Am I correct that there is a different set of temperature wires then for the retarder?
If the retarder gets warmer, will it raise the temperature on the tranny?

Larry,

1 the temp sensor for the retarder is completely different and it should feed the info to the diagnostic plug. Now with that being said some of the early models that info is hard to get through the Silverleaf VMS system but doable.

2. If you are on the retarder hard yes you can overheat as Dave has mentioned. You have to dissipate that energy somewhere and the oil gets hot and then it is cooled as it passes through the trans. oil cooler.

3 And yes your coach will accept the Silverleaf system.
Pamela & Mike

Re: Transmission temp gauge

Reply #8 – July 18, 2015, 08:57:41 am

P &M, thanks for the info. I thought they were separate. So far, I have only used the retarder in the 1st position when slowing. Silverleaf will be on the list, but the steep uphill curve needs to flatten a little.

Thanks, Larry

Re: Transmission temp gauge

Reply #9 – July 18, 2015, 09:21:43 am

The retarder on Position 1 will have very little effect. The next time you are driving try some more positions, and give it some seconds to respond.

I learned after my connection got loose due to water on the road, the high temp alarm and light may come on. The solution was to reconnect the loose wire. Also the retarder would not work, as the computer put it in safe mode. The Allison shop read the code and reset the computer. But the safe mode is to keep the transmission from overheating due to retarder use. Above the safe temp. the retarder will not activate

Allison tech explained, that it is very hard to damage the Allison transmission. All the garbage trucks they service have the retarder, and he never sees them damaged even by the hourly employees in hard service. He said just watch the gauge and back off if you see temps above 250 and climbing.

Re: Transmission temp gauge

Reply #10 – July 18, 2015, 09:53:00 am

P&M does your 97 show the retarder temp? How can I do that if so?

I was also told that the trans gear indicators do not show on our 97's?

Thanks for any help.

Bob

Re: Transmission temp gauge

Reply #11 – July 18, 2015, 10:19:40 am

Quote from: Caflashbob – July 18, 2015, 09:53:00 am

P&M does your 97 show the retarder temp?
How can I do that if so?
I was also told that the trans gear indicators do not show on our 97's?
Bob

Bob,
1 Yes
2 Depending on how your ECM is set up it should be on PID 120, 121, or 122 if not there then you need to talk to the IT people at Silverleaf and they can help find the right PID address.
3 correct, Even though you have the touch pad that shows gear selected & gear in use this info isn't read by the Silverleaf unless they have upgraded there software. You will need to check with there IT people on that also.

Pamela & Mike

Re: Transmission temp gauge

Reply #12 – July 18, 2015, 12:11:22 pm

Larry
Another thing to consider for your transmission is synthetic fluid- much better for dissipating heat. Heat is the enemy of our transmissions, so if you do not have synthetic fluid in it, look at getting it changed over at your next service.

I use Amsoil Torque Drive in mine, others use Transyd.

Watch your temps and enjoy the ride.

Re: Transmission temp gauge

Reply #13 – July 18, 2015, 04:29:38 pm

The big concern is the retarder oil temp as it returns to the sump, am told max temp is 300f, that can be reached easy & quickly. I have the VMSps display both trans & retarder. On long steep grades, I slow to 4th gear, use 2nd notch retarder, down about 45 mph retarder runs about 230f engine water goes up to about 200f. Pulling retarder stick to max, the temp goes crazy, give it a try if your reading it. Educational.

Re: Transmission temp gauge

Reply #14 – July 18, 2015, 09:52:33 pm

Quote from: Pamela & Mike – July 18, 2015, 10:19:40 am

Bob,
1 Yes
2 Depending on how your ECM is set up it should be on PID 120, 121, or 122 if not there then you need to talk to the IT people at Silverleaf and they can help find the right PID address.
3 correct, Even though you have the touch pad that shows gear selected & gear in use this info isn't read by the Silverleaf unless they have upgraded there software. You will need to check with there IT people on that also.

Pamela & Mike

No update available.

The PID's mentioned are retarder not trans?

Re: Transmission temp gauge

Reply #15 – July 19, 2015, 12:52:44 pm

Just confirming or "seconding" John S, as well as Don & Tys, Silverleaf is a great investment. The PC version is only ~$400, as compared to $4,000 for some of the versions with a box. Their tech support team is fabulous by phone. Highly recommended when Silverleaf can be added to your list of coach upgrades — early in your ownership, if possible (you know we only purchased 60 days ago).

Watching the difference between the analog gauges and the Silverleaf system on a 2,000 mile trip to Rhode Island, which included serious grades on I-26 in western North Carolina, there was a SIGNIFICANT difference in movement on the analog gauge (very little) and the Sliverleaf transmission temperature. There is supposed to be an even more precise measurement of retarder temps, if I understand the documentation, but our 1999's nine-pin diagnostic plug doesn't seem (?) to supply that info.

Still, the overall transmission temperature registered significantly higher on the Silverleaf and allowed us to manage gear selection and retarder position well. Best of all (which is why we have retarders), we could establish a gear and retarder combination that permitted descent at exactly the speed we wanted without EVER touching the brakes. They would have been completely fresh, if needed for a faster-than-anticipated stop.

Re: Transmission temp gauge

Reply #16 – July 19, 2015, 01:39:28 pm

Quote

There is supposed to be an even more precise measurement of retarder temps, if I understand the documentation, but our 1999's nine-pin diagnostic plug doesn't seem (?) to supply that info.

Try PID 120. Works on my M11. Scary how fast it rises.

Re: Transmission temp gauge

Reply #17 – July 19, 2015, 02:18:09 pm

Quote from: Pamela & Mike – July 18, 2015, 10:19:40 am

Bob,
1 Yes
2 Depending on how your ECM is set up it should be on PID 120, 121, or 122 if not there then you need to talk to the IT people at Silverleaf and they can help find the right PID address.
3 correct, Even though you have the touch pad that shows gear selected & gear in use this info isn't read by the Silverleaf unless they have upgraded there software. You will need to check with there IT people on that also.

Pamela & Mike

Mine shows the trans temp not the retarder. You sure yours is the retarder?

I had a trans heat warning I made go off on purpose with the dash warning light but the dash gauge and the silverleaf both were not that hot.

Seems to me the warning circuit is separate somehow for the retarder part.

Re: Transmission temp gauge

Reply #18 – July 19, 2015, 02:40:00 pm

Bob,

We can read both but have had help from a Cummins field rep to accomplish this.

The trans temp and retarder temp come from different sensors that feed the ECM. If you have a 4060R world, if the retarder sensor gets too hot it will start shedding load. Dash gage comes from its own sensor.

Pamela & Mike

Re: Transmission temp gauge

Reply #19 – July 19, 2015, 02:44:29 pm

As mentioned by others, you can clearly see the trans retarder temp go up rapidly with application and eventually the trans sump temp rises as some of the heat is absorbed through circulation, as well as the retarder temp falling when RPM's are brought up while downshifting and retarder setting is reduced. There can be found a sweet spot in most situations where the retarder temperature peaks at an acceptable level to provide the desired amount of speed control/gear selection/RPM. One of the most valuable functions of the VMSPC system in my opinion. here is a screen shot when the coach is warming up showing the retarder temperature lower than the trans sump because it hasn't been used yet and the trans fluid is just starting to warm up. When the coach is fully warmed up, the retarder has been used some but has been off for awhile, the temperature of the retarder and the trans sump will be equal or nearly so.
Don

Quote from: Caflashbob – July 19, 2015, 02:18:09 pm

Mine shows the trans temp not the retarder. You sure yours is the retarder?

Re: Transmission temp gauge

Reply #20 – July 19, 2015, 03:41:51 pm

Thanks for the screen shot. Like several things. 9.0 to 9.6mpg is good. Flat ground?

Re: Transmission temp gauge

Reply #21 – July 19, 2015, 05:05:52 pm

Bob,

Thanks! We'll use PID 120 for the retarder. That plus the transmission itself should give us a good picture. Love Silverleaf! Nice photo Don & Tys. Susan & I are always interested in how others use the screen real estate: what gauges, where placed, etc. Helpful!

Re: Transmission temp gauge

Reply #22 – July 19, 2015, 10:13:33 pm

Our coach came from the factory with dash transmission temperature gauge sender screwed into the large transmission coolant hose that comes FROM the transmission cooler. I changed it to the other large coolant hose that goes TO the cooler. These are the hoses that are connected to the lower front-facing part of the transmission.

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