intermitant retarder

Topic: intermitant retarder (Read 1598 times) previous topic - next topic

intermitant retarder

December 30, 2011, 02:21:06 pm

I have a friend travelling in mexico who is having trouble
with his retarder. sometime it works, sometimes it doesn't
his coach is a 36' 98 U-320.
any thoughts would be appreciated.

thanks wayne

Re: intermitant retarder

Reply #1 – December 30, 2011, 03:01:36 pm

Wayne, have your friend check to see if the brake light's are stuck on, if they are it will not retard,he has a bad brake light switch.

Re: intermitant retarder

Reply #2 – December 30, 2011, 06:30:39 pm

I had the exact same problem. At the Allison shop the fault code was temp sensor. The mecanic when under and found the retarder wiring harness was broken in the switch. Parts alone $900.00 plus new trns synd ,10 gallons, filters and labor $1998.00

Re: intermitant retarder

Reply #3 – December 30, 2011, 11:41:23 pm

Quote from: Wayne Macauley – December 30, 2011, 02:21:06 pm

I have a friend travelling in mexico who is having trouble
with his retarder. sometime it works, sometimes it doesn't
his coach is a 36' 98 U-320.
any thoughts would be appreciated.

thanks wayne

Nice to have the retarder when you want it especially in unfamiliar areas. If no solutions from the forum, here is an interactive map of Allison facilities in Mexico: Allison Transmission Cost for work should be much less than here.

Re: intermitant retarder

Reply #4 – December 31, 2011, 12:30:28 am

Check for a loose wire on the Allison computer. The computer has several large plugs. Each plug has many individual wires, each with a 'pin' terminator that plugs into the large plugs. Each wire must be pushed fully in as a wire partially touching would cause the problem. It took Allison over 2 days with several part changes and test drives to find our single loose wire. Our Allison computer is located behind kick panel to the left of driver's chair, located near floor.

Re: intermitant retarder

Reply #5 – January 03, 2012, 11:06:57 pm

Quote from: Barry & Cindy – December 31, 2011, 12:30:28 am

Check for a loose wire on the Allison computer. The computer has several large plugs. Each plug has many individual wires, each with a 'pin' terminator that plugs into the large plugs. Each wire must be pushed fully in as a wire partially touching would cause the problem. It took Allison over 2 days with several part changes and test drives to find our single loose wire. Our Allison computer is located behind kick panel to the left of driver's chair, located near floor.

Is the kick panel the panel with the drink holder on top and is mounted against the driver side coach wall? If not, I do not understand where this kick panel is located.

Thank you.

Re: intermitant retarder

Reply #6 – January 03, 2012, 11:15:36 pm

The kick panel is the vertical panel to the left of the driver's left foot.

Re: intermitant retarder

Reply #7 – January 04, 2012, 08:39:45 am

RE: Is the kick panel the panel with the drink holder on top and is mounted against the driver side coach wall?

I am remembering that the Allison computer is located behind the forward carpeted side piece that comes off by removing screws buried in the carpet.

The side carpeted piece to the left of the driver's foot and the front carpeted piece in front of the driver's feet are all one piece of wood and come off together.

Does the flat black vertical side panel under the side dash switches and drink holder come off?

Re: intermitant retarder

Reply #8 – August 03, 2018, 08:14:39 pm

I'm going to revive a very old thread as. 1, The coach in question was Reg's coach in B.C. the one I now own and it is doing the same thing as it did to him. 2, There never was a resolution posted as to the issue being resolved. 3, I removed the kick panel (the one with the foot well heater vent. No "black box" there. So would this black box be under the shift pad and that big switch panel? Reg had tile installed so I see no way to remove the black vertical panel that the switch panel screws to. Does this panel come off or would removing the switch panel suffice?

Update. I removed the switch panel and still no "black box" The wire bundle that exits the shifter pad has a connector of a rather complicated design. Not sure how it comes apart. As you recall. I had this shifter pad and retarder stick replaced. I followed the wire bundle to under the dash and it exits through the floor and comes out again in the Gen radiator bay and heads towards the center of the chassis. And that's as far as I can go.

Advice is appreciated. One more thing. The symptoms are that "most" of the time if I stop and turn the key off and restart it will work "for a while" but is happening more often. Sure seems like a loose wire type of thing going on.

Re: intermitant retarder

Reply #9 – August 03, 2018, 09:35:53 pm

The complex plug that goes to the back of the retarder panel is known to be prone to intermittent connections. Some folks have success in unplugging/plugging it in. I'm experiencing the same thing to a lesser degree, sometimes just turning on the retarder rocker doesn't invoke it, I have to give a tap of brake to wake it up.

My plan is to unplug, inspect, spray both sets of contacts with Deoxit D5 and see if that fixes it. If not will repeat the process at far end of harness, a plug there as well. Might give it a try.

Re: intermitant retarder

Reply #10 – August 03, 2018, 10:31:35 pm

Quote from: Chuck Pearson – August 03, 2018, 09:35:53 pm

The complex plug that goes to the back of the retarder panel is known to be prone to intermittent connections. Some folks have success in unplugging/plugging it in. I'm experiencing the same thing to a lesser degree, sometimes just turning on the retarder rocker doesn't invoke it, I have to give a tap of brake to wake it up.

My plan is to unplug, inspect, spray both sets of contacts with Deoxit D5 and see if that fixes it. If not will repeat the process at far end of harness, a plug there as well. Might give it a try.

Retarder panel? Or was that the shifter pad? I pulled off the joy stick connection and gave it a bit of a clean. But I don't have any deoxit spray. But it's on the shopping list.

Re: intermitant retarder

Reply #11 – August 03, 2018, 10:31:53 pm

The rebuild guys said to pull the plugs and reinsert ten times at all ends

Re: intermitant retarder

Reply #12 – August 04, 2018, 09:33:54 am

If connections are suspect, be sure to use De-Oxit as you unplug/plug/unplug .......

Re: intermitant retarder

Reply #13 – August 04, 2018, 04:55:53 pm

Quote from: wolfe10 – August 04, 2018, 09:33:54 am

If connections are suspect, be sure to use De-Oxit as you unplug/plug/unplug .......

Not to harp on it, but DeOxit D5 truly needs to be in everyone's arsenal. Plugs, switches, if your Dometic thermostat buttons are wonky pull the outer cover, a short spray on the little microswitches (no need to dissassemble switches) has fixed mine for two years now. It is more than contact cleaner, some of which can have disastrous results on incompatible plastics. (CRC for instance, personal experience.)

Also, I see many refer to using dielectric grease on electrical connections and it does have its uses but it is an insulator, not a conductant. Not what you want on your small level signal pins.

Re: intermitant retarder

Reply #14 – August 04, 2018, 06:59:23 pm

Quote from: wolfe10 – August 04, 2018, 09:33:54 am

If connections are suspect, be sure to use De-Oxit as you unplug/plug/unplug .......

Have some DeoxIT D5 cleaner and S5 sheild on order from CAIG. No one carries it out here in the hinterlands of Eastern Wa.

Re: intermitant retarder

Reply #15 – August 04, 2018, 08:22:42 pm

Check for ABS sensor problem. The ABS has to work for the retarder to work. This condition can reset on start up and fail while driving especially in stop and go traffic.

Re: intermitant retarder

Reply #16 – August 04, 2018, 08:24:55 pm

Quote

I removed the kick panel (the one with the foot well heater vent. No "black box" there.

BigDog, did you ever find the Allison box? Here's where it is on a 97 and a 99 so yours should be the same.
jor

Re: intermitant retarder

Reply #17 – August 05, 2018, 12:18:38 am

Quote from: jor – August 04, 2018, 08:24:55 pm

BigDog, did you ever find the Allison box? Here's where it is on a 97 and a 99 so yours should be the same.
jor

I sure didn't Jor. Just a couple of cables running through that area. The cable that exits the Shift pad connects to a cable in that area and goes down through the floor into the Gen Radiator area (no box there that I could see) and the cable continues towards the center of the coach. Which is as far as I could follow the cable. I'm not sure what's up. I'll try and take a picture on Sunday.

Re: intermitant retarder

Reply #18 – August 05, 2018, 12:28:11 am

Quote from: Chuck Pearson – August 04, 2018, 04:55:53 pm

................DeOxit D5 truly needs to be in everyone's arsenal.........................Also, I see many refer to using dielectric grease on electrical connections and it does have its uses but it is an insulator, not a conductant. Not what you want on your small level signal pins...........

Chuck,
+1 on the DeOxit.

But regarding the Dielectric grease, it's incredible how some old wives tales cannot be stopped! They just will not DIE!

50 Amp Cable End

You are ascribing the wrong characteristics, regarding the "dielectric" in the product name, as you discourage Foreforum readers from using known good dielectric grease products that can help us all.

Dielectric greases ARE non-conductive. HOWEVER, when you slide the connection together, even in very low (e.g. - pico amp and microvolt) applications, there is metal-to-metal contact in the connection. Being of high lubricity, the dielectric grease gets entirely displaced and the void/volume around the actual electrical connection is protected from humidity/moisture/Oxygen reaching the conducting elements. Therefore, oxidation/reduction reactions are significantly slowed if not completely stopped.

If you have an intermittent connection, most of the time (I would guess 90% or greater) it is because the actual conducting elements of the problematic connection have slightly or even significantly oxidized/corroded, preventing reliable contact. Some circuitry uses gold or silver plating to reduce this, but those instances are by far the minority of circuits.

Now, if the "corrective" grease that you apply happened to be "conductive" it would be far too easy to get "bleed" from one pin to another in, for example, a multi-pin connector or an IC chip socket. If the grease got hot, liquified and spread; (Duh, that's why Dow and Loctite (as examples) call it dielectric as well as why you don't want to use a "conductive grease" in such corrective applications.

If you want more scientific insights, there are Mil Specs and Engineering standards for dielectric greases. I have used specified dielectric greases for years in Nuclear Navy electronics applications and for many more years in commercial Nuclear Power instrumentation and control systems, as well as in everyday coach and equipment applications.

With just a cursory review of the Mil Specs and Engineering Standards, you will see that the specifications principally deal with appropriate application temperature ranges (- 50 F to + 1000 F not unusual), deal with the dielectric grease's insolvency in water, deal with the lubricity of the grease (how easily it gets displaced in sliding a connection together), etc. There is nothing about any insulation resistance provided by the dielectric grease.

You CAN find ranges of resistance to current, under varying environmental conditions, but those are specified in the Mil Specs and Engineering standards for Conductive greases. But you are condemning the use of Dielectric greases, not the use of Conductive greases.. Conductive greases have a whole different range of purpose.

When applying a dielectric grease in a contained/protected (enclosed) connection, using a good bit more grease than a film is usually a wise idea, since it protects the electrical connection from corrosion by displacing water and reducing or eliminating exposure to moisture/oxygen. If the electrical conductor surfaces are not contained/enclosed, for example, with your 50 or 30 amp plug prongs or with your towed electrical connectors, then stick with a liberal film, and clean/replenish the film more frequently. You will not only help yourself, but some future users of that 50 amp outlet.

If the contact of the two electrical surfaces (needed to pass current or voltage) is such that enough grease remains between them and, in turn, causes a circuit connectivity problem, then you've got other problems, far worse problems with that connection (that's when a conductive grease MIGHT help or even save the day). But any sliding/wiping/bolted/terminated (like a screw terminal) connection, either for large current and voltage or for small current and voltage, will be tight enough that it forces the dielectric grease out of the way. That is why the dielectric grease specification details the lubricity for a particular grease and the circuitry application that the specification addresses.

Just off the top of my head, about the only types of electrical connections on a motorcoach, that a dielectric grease would not be beneficial for, are any type of armature/brushes and the contacts of a relay or solenoid.

HTH,
Neal

Re: intermitant retarder

Reply #19 – August 05, 2018, 01:00:00 am

Neal, I wasn't trying to promote, nor was I aware of any old wives tale regarding dielectric grease. Like many other posts my stance on this is based on personal experience. I am aware of the key points of your exhaustive rebuttal, most notably the fact that tight fitting connections will displace this grease allowing contact. Great on mil spec pins, less so on loose, worn contact surfaces on 20 year old motorhomes.

No confusion between dielectric and conductive grease here, but probably should have said if you're using dielectric grease at least clean contact surfaces with deoxit or similar prior to application.

Re: intermitant retarder

Reply #20 – August 05, 2018, 02:26:44 am

The Allison ECM (control box) on our 99' U270 is in the main storage compartment on the rear compartment wall towards the street side. Sorry I don't have a picture handy, but it is a silver flat box like structure with three large multi pin plugs on it.
Don

Quote from: bigdog – August 05, 2018, 12:18:38 am

I sure didn't Jor. Just a couple of cables running through that area. The cable that exits the Shift pad connects to a cable in that area and goes down through the floor into the Gen Radiator area (no box there that I could see) and the cable continues towards the center of the coach. Which is as far as I could follow the cable. I'm not sure what's up. I'll try and take a picture on Sunday.

Re: intermitant retarder

Reply #21 – August 05, 2018, 02:56:56 am

Quote from: Don & Tys – August 05, 2018, 02:26:44 am

The Allison ECM (control box) on our 99' U270 is in the main storage compartment on the rear compartment wall towards the street side. Sorry I don't have a picture handy, but it is a silver flat box like structure with three large multi pin plugs on it.
Don

Thanks Don & Tys. I'll have a look in the main storage bay tomorrow. That would be a very easily accessed & convenient place for it. Probably why I didn't look there.

Re: intermitant retarder

Reply #22 – August 05, 2018, 03:41:42 am

I have an abs light on and the retarder works fine

Re: intermitant retarder

Reply #23 – August 05, 2018, 05:36:45 pm

Don & Tys. Thanks a bunch. The back wall of main storage bay on street side is where it is, Partialy obscured by the tool drawers. But still going to be worlds easier to monkey with the connectors than laying on the floor under a steering wheel. Thanks again for the hint.

Re: intermitant retarder

Reply #24 – August 07, 2018, 08:41:10 pm

I haven't had a visit from UPS with my Deoxit yet. However. I did pull the control panel on the left and removed the joystick plug and gave it a clean with a bit of emery cloth.

I have had the occasion to drive the coach the last two days. Some in-town stop and go as well as a bit of highway. The retarder has been behaving nicely. In addition. It is doing something it hasn't done before. And that would be that with the retarder rocker switch "on" and the joystick at zero. I'm getting retarder activation based on brake application pressure. This coach has NEVER done that. And of course I didn't know that it was supposed to. So perhaps that has cleared up my intermittent issues. Will also go through and clean the other Alison connectors when the Deoxit comes in.

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