tranny light after start

Topic: tranny light after start (Read 938 times) previous topic - next topic

tranny light after start

July 19, 2020, 01:56:57 pm

1994 U280 8.3 Cummins, 3060 Allison...sometimes .....after initial engine start of the day, the check transmission light flickers on and off accompanied by the lights on the shifter control, then after a bit light remains steady and "chicken feet" appear in the shift control, after a bit of idling (charging at 14v in the gauge), a shut off and restart all ops normal

Re: tranny light after start

Reply #1 – July 19, 2020, 02:16:44 pm

Using the shift pad, check for transmission DIAGNOSTIC CODES:

Ignition on, engine off

Push shift pad up and down arrows at the same time.

Yours is right at the cusp of having fluid level checked from this shift pad. If you have this feature, you will see OL come up. If it does, push the up and down arrows again at the same time. That will bring up d-1.

If you do not have fluid level check, the first push of the up and down arrows will bring up d-1.

If there is a stored code, you will get d-1 then numbers. Copy them down. If no stored codes you will get d-1 and - -.

If there is a d-1 code, after recording it, push the mode button to go to the next diagnostic code. Repeat until you get d- "whatever" and - -.

Go to your Allison manual or online to see what the codes are.

And always with electronic controls, verify that voltage is 12+ VDC. All kinds of strange thing happen when a computer is supplied with insufficient voltage.

Re: tranny light after start

Reply #2 – July 19, 2020, 02:18:18 pm

Quote from: Tomibach – July 19, 2020, 01:56:57 pm

...light remains steady and "chicken feet" appear in the shift control...

If the photo below looks similar to what you are calling "chicken feet", that may possibly be a early warning sign of impending Allison ECU failure. But there is hope! Read through the thread below for some pertinent information:

No start, with Allison "snake eyes" (Problem Solved)

Re: tranny light after start

Reply #3 – July 19, 2020, 04:17:55 pm

well as luck would have it, all acted normal when I tried just now...I did the simultaneous up n down arrows and:

D1 code 35, secondary code 0 0 "power interruption"
D2.code 6 9, secondary code 3 2 "SPI communications link fault in ECU"
D3. - - ,

Im suspecting start batteries low voltage MAY be a cause, they are rather old red tops, and I have slated them for replacement anyway read the codes fingers crossed its start battery voltage...NEVER occurs after engine has run 5 minutes (or less) then shut down and restarted, tends to only occur after coach hasn't been started for 2-3 days, used to never occur when "boost" was used, now the off time it occurs, it does so whether boost is used or not, fluid is not the issue as recently changed, level is good, and color is clear pink....so I've cleared the codes, see if they return, lets do the planned start battery change and we'll report back further,

thanks for all the input...Tommy

Re: tranny light after start

Reply #4 – July 19, 2020, 04:20:13 pm

Quote from: wolfe10 – July 19, 2020, 02:16:44 pm

Using the shift pad, check for transmission DIAGNOSTIC CODES:

Ignition on, engine off

Push shift pad up and down arrows at the same time.

Yours is right at the cusp of having fluid level checked from this shift pad. If you have this feature, you will see OL come up. If it does, push the up and down arrows again at the same time. That will bring up d-1.

If you do not have fluid level check, the first push of the up and down arrows will bring up d-1.

If there is a stored code, you will get d-1 then numbers. Copy them down. If no stored codes you will get d-1 and - -.

If there is a d-1 code, after recording it, push the mode button to go to the next diagnostic code. Repeat until you get d- "whatever" and - -.

Go to your Allison manual or online to see what the codes are.

And always with electronic controls, verify that voltage is 12+ VDC. All kinds of strange thing happen when a computer is supplied with insufficient voltage.

and yes sir as my electronics instructor once said, "electrons don't always go where they supposed to"

Re: tranny light after start

Reply #5 – July 20, 2020, 02:59:58 pm

Quote from: Tomibach – July 19, 2020, 04:17:55 pm

D2.code 6 9, secondary code 3 2 "SPI communications link fault in ECU"

...read the codes fingers crossed its start battery voltage...

I wish you luck with your crossed fingers approach.

If positive thinking doesn't eliminate the problem, then you can expect it to get progressively worse. Eventually, you will come out one morning and try to start your engine, and it won't start. You will have snake eyes on the Allison touch pad, and you will be dead in the water. I hope you are parked in a nice location at that point, cuz you'll be there a while.

Did you read the thread I mentioned in Reply #2? There is a link in that thread to Transmission Instruments, and the trouble shooting page linked below. Pay particular attention to what it says about fault code 69-32:

Troubleshooting

Re: tranny light after start

Reply #6 – July 20, 2020, 03:14:22 pm

A call to John at Transmission Intruments wouldn't hurt. He will know what's wrong and what you should do.

Re: tranny light after start

Reply #7 – July 21, 2020, 01:26:40 pm

'preciate all the info!

Re: tranny light after start

Reply #8 – July 21, 2020, 01:31:08 pm

Quote from: Chuck & Jeannie – July 20, 2020, 02:59:58 pm

I wish you luck with your crossed fingers approach.

If positive thinking doesn't eliminate the problem, then you can expect it to get progressively worse. Eventually, you will come out one morning and try to start your engine, and it won't start. You will have snake eyes on the Allison touch pad, and you will be dead in the water. I hope you are parked in a nice location at that point, cuz you'll be there a while.

Did you read the thread I mentioned in Reply #2? There is a link in that thread to Transmission Instruments, and the trouble shooting page linked below. Pay particular attention to what it says about fault code 69-32:

in actual fact my optimistic approach is based on a. friend's coach having the same issue, and it disappeared when he replaced his chassis batteries...will update

Troubleshooting

Re: tranny light after start

Reply #9 – July 23, 2020, 11:53:25 am

Just out of curiosity, is the transmission being lubed if the engine is already running and the Fault occurs, why won't it let you start the engine

Re: tranny light after start

Reply #10 – July 23, 2020, 12:18:45 pm

Quote from: Tomibach – July 23, 2020, 11:53:25 am

Just out of curiosity, is the transmission being lubed if the engine is already running and the Fault occurs, why won't it let you start the engine

The "No Engine Start" scenario occurs when you get the snake eyes on the Allison touch pad before you crank the engine. There is a electronic interlock in the Allison brain box that prevents the engine from starting unless the neutral indicators (NN) are showing on the touch pad.

I have not heard of anyone getting the snake eyes after the engine is running. New one on me.

Re: tranny light after start

Reply #11 – July 23, 2020, 12:25:54 pm

Yes, snake eyes can occur both before start up and while running.

It indicates a serious issue with transmission/transmission electronics.

That should throw a DIAGNOSTIC CODE that you can retrieve from the shift pad as has been discussed many times.

If the snake eyes persist, it is time for John: Transmission Instruments HE DA MAN!

Re: tranny light after start

Reply #12 – July 23, 2020, 12:30:09 pm

Well now you have, turn on the switch, start the engine, indications on control pad flash on and off along with transmission light then snake eyes, still haven't done the batteries they test ok but are 11 yr old red tops, I'm also headed underneath to check and clean connectors

Re: tranny light after start

Reply #13 – July 23, 2020, 12:31:51 pm

Yes threw the codes, thing is it's extremely intermittent and has never occurred while driving...have reviewed the codes

Re: tranny light after start

Reply #14 – July 23, 2020, 12:37:34 pm

So, what are the the codes/what do the codes indicate is the problem?

Re: tranny light after start

Reply #15 – July 23, 2020, 12:54:16 pm

In Reply #3, the OP reported two stored codes:

D1 code 35, secondary code 00 "power interruption"
D2 code 69, secondary code 32 "SPI communications link fault in ECU"
D3 - -

Re: tranny light after start

Reply #16 – July 23, 2020, 02:10:04 pm

Quote from: Chuck & Jeannie – July 23, 2020, 12:54:16 pm

In Reply #3, the OP reported two stored codes:

D1 code 35, secondary code 00 "power interruption"
D2 code 69, secondary code 32 "SPI communications link fault in ECU"
D3 - -

ok folks, here's more to the mystery....tested batteries, in spite of age they pass the test....boost on, turn the ignition switch to "ON", fault occurs and goes to snake eyes so fast no chance to even pull codes..turn off the switch....connect an AGM battery charger and leave it a few hours...(remember batteries previously tested good, volts and CCA)....now the day has warmed up....turn the switch on, indicators on pad flash intermittently...start the engine...flash intermittently continues 2-3 minutes then stabilizes to normal indications, selected all gear selections, ops normal...shut down engine...ignition switch back on pulled code 69-32..."SPI communications link fault in ECU"....there we stand.....will call the folks as recommended at transmission instruments, AFTER I check and clean all connectors...thanks again...

Re: tranny light after start

Reply #17 – July 23, 2020, 02:19:58 pm

What you can do before contacting John (above):

Check that all connections from chassis battery to dash (both positive and ground) are clean and tight.

Unplug and replug both shift pad and Allison ECU (under driver's side of dash). If you have an electrical contact cleaner, use it on the pins.

Have you checked for proper voltage at the dash when this happens (raise dash)?

Re: tranny light after start

Reply #18 – July 23, 2020, 02:35:50 pm

Quote from: wolfe10 – July 23, 2020, 02:19:58 pm

What you can do before contacting John (above):

Check that all connections from chassis battery to dash (both positive and ground) are clean and tight.

Unplug and replug both shift pad and Allison ECU (under driver's side of dash). If you have an electrical contact cleaner, use it on the pins.

Have you checked for proper voltage at the dash when this happens (raise dash)?

im not much of an electrician, more eng and tranny guy, but I can do the multimeter thingy...had the dash open, several relays , which one should I check the voltage at?..the one clicking on and off when this happens?

the ECU is under the dash??...sure would be nice to have a diagram of what's what under the dash ....my transmission book shows the ECU on the right side of the transmission itself

Re: tranny light after start

Reply #19 – July 23, 2020, 02:38:35 pm

Shouldn't be any relay under the dash clicking on and off with the ignition on. The IGNITION RELAY/SOLENOID may be failing.

When this happens, do you loose other functions that only work with the ignition on? Turn on the dash HVAC fan-- easy to tell if it keeps working with the ignition on or stops when you have the other symptoms.

Re: tranny light after start

Reply #20 – July 23, 2020, 03:09:40 pm

Quote from: wolfe10 – July 23, 2020, 02:38:35 pm

Shouldn't be any relay under the dash clicking on and off with the ignition on. The IGNITION RELAY/SOLENOID may be failing.

When this happens, do you loose other functions that only work with the ignition on? Turn on the dash HVAC fan-- easy to tell if it keeps working with the ignition on or stops when you have the other symptoms.

no other symptoms, sounds like a click turning on and off the transmission light...anybody with a 1994 U280 Unihome care to give me a tour under the dash?

Re: tranny light after start

Reply #21 – July 23, 2020, 03:27:06 pm

When you raise the dash, there will be a label on the part that lifts.

It will show you which TWO fuses go to the Allison (one for memory and one for "run").

Outboard of the fuse boxes is the ground strip. Check that all the nuts on it are tight.

Check voltage between the ground strip and the 15 amp Allison fuse when this happens. That will tell you if power is leaving the fuse box headed to the ECU.

If the 280 is like the 240, the ECU and its two gang plugs are easy to see if you lie on the floor and look above the brake pedal.

Re: tranny light after start

Reply #22 – July 23, 2020, 03:43:46 pm

Quote from: wolfe10 – July 23, 2020, 03:27:06 pm

When you raise the dash, there will be a label on the part that lifts.

It will show you which TWO fuses go to the Allison (one for memory and one for "run").

Outboard of the fuse boxes as the ground strip. Check that all the nuts on it are tight.

Check voltage between the ground strip and the 15 amp Allison fuse when this happens. That will tell you if power is leaving the fuse box headed to the ECU.

If the 280 is like the 240, the ECU and its two gang plugs are easy to see if you lie on the floor and look above the brake pedal.

ok thanks, will report further, right now its operating normally as it seems to do after the sun has hit the dash fir a bit (huh?)..

Re: tranny light after start

Reply #23 – August 01, 2020, 11:37:36 am

well, read all the posts, checked everything I possibly could, swapped out the shift pad with a friends, problem stayed in my coach, got the same codes, it would fault immediately on switching on the ignition, pointed a small space heater at the trans ECU behind the steering column for about 20 minutes...presto..ops normal, ....for now...looks like a trip to the Transmission Instruments folks for my ECU...even their own troubleshooting section says code 69-32 don't even bother with the trouble shooting procedure, send it here, we can fix it

so now another question, is there any trick to removing the ECU?...seems to be connected at the head by some small screws...what is it connected to?...anything easy to damage??

note: crow pie is nice with cool whip

Re: tranny light after start

Reply #24 – August 01, 2020, 01:06:30 pm

Quote from: Tomibach – August 01, 2020, 11:37:36 am

...is there any trick to removing the ECU?...

Nothing tricky. Unplug the connectors - remove the mounting screws. Photos (link below) of what I sent in for rebuild.

No start, with Allison "snake eyes" (Problem Solved)

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