Skip to main content ↑ ↓
Topic: Troubleshooting Speedometer Problems (Read 1359 times) previous topic - next topic

Troubleshooting Speedometer Problems

Can someone give me a troubleshooting list for checking my speedometer head and sending unit which I assume is on the transmission? Speedometer quit a couple of years ago and it was shop repaired along with other items. Shop is no longer in business. No parts were needed and the difference that time was the cruise control would not work either. This time the cruise works but the speedometer does nothing. I have checked the fuse. Reading past posts it appears that these speedometers (1991) were bad to fail. I don't mind replacing the head but would like to be sure that is the problem. Also what is the replacement? I just replaced my light switch and it was an International.
Thanks for your help.
Jerry
'91 U240 GV / 36'
CAT 3208 w/Allison MT 643  4 speed
'10 Ford Flex

Growing old is mandatory
Growing up is optional

Re: Troubleshooting Speedometer Problems

Reply #1 –
Jerry since no one has responded to your post I would just say that if it were me I would take it out and send it to these folks to have it checked out or repaired. Lauderdale Speedometer and Compass

Mark

The selected media item is not currently available.
Mark and Tanya
Milton , Florida
US Navy Veteran (DV)
1999 U270 Special 40' CAI , 2015 Jeep Wrangler Sahara

Re: Troubleshooting Speedometer Problems

Reply #2 –
Jerry,

You need to check the speed generator on your trans. also. The speedometer may be OK. Do you know which trans. you have?

These folks helped us out when we had a similar problem on our '92- U240 :  Instrument Exchange 713-923-6104 in Houston , this is the last # I had for them.

Pamela & Mike
Pamela & Mike 97 U 320

"It's not what happens to you, but how you react to it that matters."

Re: Troubleshooting Speedometer Problems

Reply #3 –
Jerry

Mine is currently at the shop getting ready for a speedo/cruise replacement....neither on mine is working.  im haveing a King Control cruise installed.  It was suggested on my earlier post to check the sending unit coming out of the trans for a repair.  I don't know if yours is the same but if you check under the coach behind the right side rear dual you can see the T shaped fitting.  One is the speedo sending unit and one is for the cruise control.  I was advised that there is a zerk fitting on it and that may have been my speedo issue.  I however was not able to get under the coach to do any of the repairs myself.  I will let you know what my shop says once i hear back.  I wouldn't think too much of a difference between your '91 and my '89

Jeff
Jeff & Carrie
2023 Geneva 31VA
1989 Grand Villa 36' ORED "The Button Pusher" - GONE 🥺

Re: Troubleshooting Speedometer Problems

Reply #4 –
Quote from: Pamela & Mike –
Jerry,

You need to check the speed generator on your trans. also. The speedometer may be OK. Do you know which trans. you have?

These folks helped us out when we had a similar problem on our '92- U240 :  Instrument Exchange 713-923-6104 in Houston , this is the last # I had for them.

Pamela & Mike

Thanks to all that responded. Pamela and Mike, my transmission is an Allison MT 643 ( 4 speed ). Jeff, please let me know what they found. I found the speedometer sending unit by the wire colors, but I am to have to raise the coach a bit to get under it. I cleaned those connections last month trying to get the transmission temp gauge working. That ended up being a wire off the dash gauge. I wondered if there was an ohm reading that I could check for on the sending unit. I'll call the # in Houston. Mark, I'll check with Lauderdale on pricing. I have had pretty good luck at the local NAPA on matching parts. Just installed a light switch this morning.
Again thanks to all,
Jerry
'91 U240 GV / 36'
CAT 3208 w/Allison MT 643  4 speed
'10 Ford Flex

Growing old is mandatory
Growing up is optional

Re: Troubleshooting Speedometer Problems

Reply #5 –
Jerry,

It has been a while but here is what I think we did to check the output of the speed generator. We had a 643 also.

 You can use a digital volt/ohm meter that can read frequency and hook it to the wires that come from the speed generator. When you drive your meter should read a freq. the same as the speedo. This will check the wiring also coming from the rear. You can make a long jumper wire and come straight off the speed generator to determine if it is faulty wire from the rear or a bad speed generator. 



Pamela & Mike
Pamela & Mike 97 U 320

"It's not what happens to you, but how you react to it that matters."

Re: Troubleshooting Speedometer Problems

Reply #6 –
You can also remove the sender and use a drill to turn it and see if the speedometer reads. If you are by yourself, you can check the sender with the drill and a volt meter on the wires disconnected form the wire harness. On ac voltage should be able to read a voltage.
previous 1984 35 ft ORED 250 HP 3208 Cat       
previous 1998 40 ft U295 CAI 325 hp Cummins
previous 2003 40 Ft u320 build #6140 450 Cummins M11.                                                         
1999 Mazda Miata
Ron, Nancy, Tipper the cat, Max The dog
1997 U 270 36 ft build number 5174 8.3 Cummins

Re: Troubleshooting Speedometer Problems

Reply #7 –
Quote from: red tractor –
You can also remove the sender and use a drill to turn it and see if the speedometer reads. If you are by yourself, you can check the sender with the drill and a volt meter on the wires disconnected form the wire harness. On ac voltage should be able to read a voltage.
Quote from: Pamela & Mike –
Jerry,

It has been a while but here is what I think we did to check the output of the speed generator. We had a 643 also.

 You can use a digital volt/ohm meter that can read frequency and hook it to the wires that come from the speed generator. When you drive your meter should read a freq. the same as the speedo. This will check the wiring also coming from the rear. You can make a long jumper wire and come straight off the speed generator to determine if it is faulty wire from the rear or a bad speed generator. 



Pamela & Mike

As I will be by myself let me ask for some clarification. With the speedometer generator removed and connected to a drill and a digital volt/ohm meter connected to the leads from the generator, do I set the meter on AC volts? and what type of reading should I expect? Should the voltage rise as the drill speed increases? Just want to be sure before I crawl under the coach and start testing.
Thanks to all.
Jerry
'91 U240 GV / 36'
CAT 3208 w/Allison MT 643  4 speed
'10 Ford Flex

Growing old is mandatory
Growing up is optional

Re: Troubleshooting Speedometer Problems

Reply #8 –
Yes ac setting and it should increase as the speed increases
previous 1984 35 ft ORED 250 HP 3208 Cat       
previous 1998 40 ft U295 CAI 325 hp Cummins
previous 2003 40 Ft u320 build #6140 450 Cummins M11.                                                         
1999 Mazda Miata
Ron, Nancy, Tipper the cat, Max The dog
1997 U 270 36 ft build number 5174 8.3 Cummins

Re: Troubleshooting Speedometer Problems

Reply #9 –
Thanks, Ron
Now if it will hold off raining, I'll pull it off and check it.
'91 U240 GV / 36'
CAT 3208 w/Allison MT 643  4 speed
'10 Ford Flex

Growing old is mandatory
Growing up is optional

Re: Troubleshooting Speedometer Problems

Reply #10 –
I pulled the speedometer generator today and first bench tested it with the drill and voltmeter. With VM set on AC the generator will run up to .93. I then reconnected the wires and turned the ignition on to power the speedometer head and again using the drill the needle never moved.. I have a couple of questions before I send the speedometer off. 1. Should the AC readings be in the hundreds and 2. Shouldn't the speedometer register using the drill to drive it?
Again thanks for any help.
Jerry
'91 U240 GV / 36'
CAT 3208 w/Allison MT 643  4 speed
'10 Ford Flex

Growing old is mandatory
Growing up is optional

Re: Troubleshooting Speedometer Problems

Reply #11 –
IF your speed-o-meter is electronic (I recently replaced one) FT has them.
They are very reasonable too.  pc

Instrument Exchange  713-923-6104 (JOE)
S/W Houston 95" U320C SE/40' 
Build #4778  Cummins M11
Repairs & Covered RV Parking (BAO)
PPL is close..

Re: Troubleshooting Speedometer Problems

Reply #12 –
Thanks PC and Pamela and Mike. Called the folks yesterday. They suggested I send the generator and speedometer head to them and let them determine what I needed. Very helpful and I am mailing the combo out today.
Thanks to all for your help.
Jerry
'91 U240 GV / 36'
CAT 3208 w/Allison MT 643  4 speed
'10 Ford Flex

Growing old is mandatory
Growing up is optional

Re: Troubleshooting Speedometer Problems

Reply #13 –
I sent my speedometer and generator to Instrument Exchange and they found nothing wrong with either. They suggested running new wiring from the dash to the generator. My question is " how difficult is that to do?" I assume there is a wiring channel between the floor and the storage boxes. Can I use the old wires to pull the new wire through the channel or was the wiring in the channel fastened in the channel during construction?
Thanks for any help or advise. By the way, the guys at at Instrument Exchange are super. Their only charge is the cost of returning my parts.
Jerry
'91 U240 GV / 36'
CAT 3208 w/Allison MT 643  4 speed
'10 Ford Flex

Growing old is mandatory
Growing up is optional

Re: Troubleshooting Speedometer Problems

Reply #14 –
@Jerry you should have some extra wires already there. Should be up under the dash on the drivers side and bent back on themselves in a wiring loam at the engine. Not that hard to find once you know they are there.

see ya
ken
The selected media item is not currently available.ken & dori hathaway & Big Agnes
🍺1992 U300 GrandVilla WTBI #4150 FOT FBP 2011
✨6V-92TA DDEC Parlor Coach 350HP Series 92
🏁2011 Nissan XTerra Pro-4X

Re: Troubleshooting Speedometer Problems

Reply #15 –
hey thanks Ken. I crawl back under the coach to see where the existing wires went and I see that they went up to the engine and I went under the front end and found what I think are the existing wires from the dash. I will look for the spare wires tomorrow. I can't help but think that is a bad connector. The wires I have seen look too good unless a squirrel or mouse chewed on them. Thanks again for the tip.
Jerry
'91 U240 GV / 36'
CAT 3208 w/Allison MT 643  4 speed
'10 Ford Flex

Growing old is mandatory
Growing up is optional

Re: Troubleshooting Speedometer Problems

Reply #16 –
The continuing saga. I sent my generator/sender and speedometer head to Instrument Exchange. They check them both and found no problem. They suggested that I check the wiring between the dash and the generator. I ohmed the wires and had no continuity. I noticed that the wires that were hard wired to the device mounted directly in front of the generator were similar in color to the wires at the dash. So I ohmed these wire to the speedometer connections and they are the same wires. I am really puzzled. 1. I don't know what this device is 2. Why are the speedometer wires connected to it? 3. Where do the wires that were connected to the generator/sender go? The most puzzling thing to me is that everything was working with this wiring configuration before my return trip home from Florida.
I hope someone familiar with a 91 can help me with this as you have done before.
By the way, Instrument Exchange suggested by passing this devise and run these wires to the speedometer. That would probably work but I don't know what I am cutting loose. I am thinking it is for the tach, but the wiring diagram says the tach is driven off the flywheel , not the tailshaft.
Jerry
'91 U240 GV / 36'
CAT 3208 w/Allison MT 643  4 speed
'10 Ford Flex

Growing old is mandatory
Growing up is optional