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Jakeman · 08-19-2022, 03:57 PM

I have a 1992 Itaska with a 5.9 Cummings and a At542 Allison 4 speed.
It has 155,197kms on it

I bought the unit in May and drove it 3500kms home.
Everything worked well except the cruise control and reverse lights.

The motorhome was parked for 6 weeks and when I took it out last week the speedometer and odometer were not working.
I checked the wiring it looks good.
The speedometer head in dash seems to power up as it goes to 0 when the key is turned on.

I want to replace the speed sensor, but can't seem to find one

Can anybody identify the sensor, or know where to track one down.
I am going to pull the head unit out to confirm the internals are spinning .

Also need to know where the reverse light switch is on transmission they never worked since i got the unit?
Please and thank you

Jim_HiTek · 08-20-2022, 04:36 PM

I owned a '94 Bounder with a Cummins and for the CC, there's a vacuum pump mounted to the inside of the frame rail where you can't see it unless you crawl under. It's around 6 feet (~1.7 mtrs) in front of the engine on the passengers side.

If that vacuum pump isn't running right, the CC won't work. Something else didn't work to due to lack of vacuum but I sold it 6 years ago so I don't recall what it was. My pump was bad so I found a new one based on the name plate and it was $360 back then 7 or 8 years ago. I mounted it on the oppose side of the frame rail so it was easier to get to and install.

Also, above that pump, in the engine bay, accessible under the bed perhaps, is a vacuum canister. With vacuum hoses going to it. Check all of that for leaks. Then on the engine, the CC device controlled by the vacuum has a small ball chain as the last link to the throttle. Those break. Check that too. They rust out or just break. Napa carries ball chains.

The Allison's of that era were famous for the speedo gear breaking so check that, screws into the tranni. Couple electrical wires to it I think. At least that's what my admittedly dim memory is saying about something I worked on 10 years ago.

donr103 · 08-20-2022, 06:56 PM

So.. if not a vacuum problem.. as stated above.. in your pictures.. you are looking at 3 parts.. on far left.. . That is signal generator.. spinning magnet sends signal to CC. And middle part is a gear reducer .. and far right.. Is speedometer drive gear.. that spins the whole set up off trans gear inside trans.. so because one gear inside trans is one type.. then adaptor will change speed of signal generator to send .. signal to cc.. could be any of your problems.. start by unscrewing outer part 1st to middle part.. then trans part.. this allows manufacturers to change tire size and still get CC to work.. and use same CC set up over many vehicles..
Any good speedometer shop will have these.. to test signal generator.. just hook up analog voltage meter and watch needle rise and fall.. you may need to inspect gearing inside reducer or in trans.. when pull trans speedometer gear.. look inside the gear.. it's plastic and can hollow out..
Good luck and keep us posted

Jakeman · 08-20-2022, 11:13 PM

Thank you, I will pull the speedometer drive, it had a new vacuum pump installed 2 years ago to repair the CC by previous owner, I have the invoice 863.00 CAD

Jakeman · 08-29-2022, 06:05 PM

I pulled the speed sensor and the ratio adapter.
The speed sensor tested good, but the ratio adapter had a seized output shaft/gear.
I disassembled it used a small punch and gave the output shaft a few very light taps, it dropped out, I removed the input shaft/gear as well.
I cleaned up both shafts on a wire wheel and washed all the old grease out of the case, I lubed the shafts and re packed the case with a bit of high temp waterproof grease and reassembled.

It worked perfect, if I really load the output shaft it will disengage, not sure if that is by design or maybe a bit of wear, in any event it works now.
I would like to order a new one, but need to know the ratio of reduction to get it, it's $190.00 new from Record nonreturnable, so would hate to get the wrong one

The part is a Record 800 series speedometer ratio adapter
(see pics)

donr103 · 08-29-2022, 08:10 PM

Thanks for the update.. I don't know.. there are too many different styles.. I guess it's too late to turn by hand and count the reduction.. sense no part numbers..
Good luck and keep us posted

Jakeman · 08-29-2022, 10:17 PM

I emailed Record on how to check the ratio, will post the reply

Jakeman · 08-30-2022, 12:42 PM

Jake,

Thank you for your email

If it isn't stamped on it then one way to check the ratio is to check the stamping on the gears inside the adapter

I will need to know the stamping number on each gear in the following order

Nut side - central gear - central gear - threaded side

Alternatively, you can send me the adapter and I can duplicate from sample

If your tires have changed then the ratio wont be any good anyways with what is already inside the adapter.

To make a correct ratio for you I will need the following information

Number of teeth on the drive gear
Number of teeth on the driven gear
Differential ratio
Rolling circumference a tire in inches "Mark tire, roll vehicle, measure with tape measure"

The final step is important in maintaining accuracy, doing the math equation will not produce an accurate measurement as the weight of the vehicle will affect the rolling distance

Hope this helps

Regards,

Matt

Jakeman · 01-25-2023, 10:43 PM

It started to be intermittent again.

I pulled the gear ratio adapter again, it turns out the gear was slipping on the output shaft.
I cleaned it up and used a small punch to remove the shaft from the gear, cleaned it with some emery cloth and put some JB weld on the shaft and reinserted it .

I took the motor-home on a 1100km trip and it worked perfectly