Speedometer sometimes jumps to 20MPH and stays there

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Jan 9, 2014 | 09:31 AM

professorman

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Speedometer sometimes jumps to 20MPH and stays there

I have a 94 Accord LX 5spd. I was changing my upper control arm and had to move my underhood fuse box out of the way to get to the nut. When I put the car back together, the speedometer now jumps to 20MPH when I turn the key. It kind of wobbles there. The first time it happened, I turned the car off and back on, and the speedo worked fine. Now, its just jumps to 20MPH whenever I turn the key. Sometimes, after i am driving for a while, eventually the speedometer will start working and keep working until I switch the car off again.

I do not know if there is anything in the underhood fuse box which would cause this problem. Is there any wire from the Vehicle Speed Sensor (VSS) that goes to the underhood fuse box?
__________________________________________________ _______________
EDIT: TUTORIAL written AFTER ej7attack and TOOLMAN1966 assisted me.

Symptoms: Speedometer stays at ~20MPH whether car is moving or stationary, when key is in the ON position.

Diagnosis: Check if your cruise control is working. If it is working, chances are that its the cluster. To prove it, unplug your Vehicle speed sensor (VSS). If the speedo is still reading ~20MPH when you turn the key, then it is definitely the speedo. See this youtube clip:http://www.youtube.com/watch?v=OZp7x...ature=youtu.be No need to replace it. Simply unplug it first.

Repair steps:

Remove gauge cluster: Refer to the Accord FAQ:
- 94-97 Gauge Cluster Removal . No need to pull apart your entire interior. My cluster black bezel is held in place by 4 screws. Read the entire treads.
- 94-97 Gauge Cluster Removal (with Pics)
Disassemble the gauge cluster to get to the circuit board for the speedometer
- 94-97 Gauge Cluster Dis-assembly
- http://www.youtube.com/watch?v=DjRGG...ature=youtu.be
- Remove the individual speedometer and pull off the individual circuit board for the speedometer (not the large one on the entire back of the cluster). This is the one for the speedometer gauge only.
Option 1: Replace the circuit board with one from a junk yard car/ebay.This is the easiest method, and it does not involve any advanced soldering techniques, so if you do not want to mess with soldering, this might be the way to go.
Option 2: Perform the test & repair that user TOOLMAN1966 said. Repair was free, so I went with the test and repair as he said.
- Quote:
  
  Originally Posted by TOOLMAN1966
  
  I had the Speedometer indicating 20mph and Odometer not working problem, half the time. The other half it worked perfectly. Mine is a 1998 Civic EX. My problem was a broken solder connection (often called a "cold solder joint") on IC1 pin 10. My circuit board is the one pictured by REVOAPPAREL in this thread on 8-15-2012. This pin is one of the epoxy (or glued) pins. I used the soldering iron to remove this epoxy from the pin before re-soldering it. (The heat kind of crumples the epoxy so it can be scraped off with the iron tip.) The Vehicle Speed Sensor signal comes into IC1 on this pin, but also on IC1 pin 12, and IC2 pins 10 and 15. __ I found which solder connection was broken in the following manner: Removed the circuit board from the speedometer/odometer mechanism (it pulls right off.) Attached a 12 volt power supply to IGN and GND. Used a voltmeter to read COS & SIN voltages. These 2 voltages tell the speedometer needle where to point. (RED voltmeter lead on COS+ and BLACK voltmeter lead on COS-.) (Don't look at the voltages with respect to GND. The speedometer doesn't see that.) When the circuit board was working correctly, the COS voltage was 5.04 and the SIN voltage was 0.26. These are logic levels ONE and ZERO. (If you remember your Trigonometry, the COS of zero is ONE and the SIN of zero is ZERO. Zero is the vehicle speed.) When the circuit board wasn't working correctly (this is when the needle would indicate 20mph IF it was attached) COS voltage was 2.47 and SIN voltage was 1.80. When I read these WRONG voltages, I started touching things and when I pushed on IC1 the voltages became correct for a moment. Then I used a probe to push against each IC1 pin individually and found pin 10 was the pin not making contact. __ A person should be able to use this technique to find a bad solder joint anywhere on the board causing incorrect speedometer readings when the vehicle is sitting still. ___ I also traced out the entire circuit board and drew a schematic. If I figure out how to post a scanned pdf of this, I'll attach it. ___This is my first post to any automotive thread. I sincerely hope this helps many of you out with your speedometer indicating 20mph problems! Enjoy Troubleshooting! ((Toolman1966 _ APRIL 14, 2013))
  
  Reference tread from ej7attack and TOOLMAN1966:
  https://honda-tech.com/forums/honda-accord-1990-2002-2/speedometer-somtimes-doesnt-work-stays-20-mph-help-2184891/ and
  https://honda-tech.com/forums/honda-accord-1990-2002-2/bad-vss-3175819/

My Notes:
It took some finesse to hold everything together to perform the test that toolman outlined. I didnt think I had enough hands.

The first step is to supply power to the circuit board by attaching a 12 volt power supply to IGN and GND. I used a motorcycle battery that I had laying around. I used a regular wire and screw one end of the wire to the battery and the other end, I use one hand to hold each of the wires to IGN and GND. Alligator clips would come in really handy here to make these contacts.
The next step is to test the voltage from COS+ and COS- or from SIN+ and SIN-. I used my other hand with the voltmeter probes being held like chopsticks to touch the terminals to measure the voltage. Again, alligator clips connections would make this a lot easier.
- Working correctly, readings should be: COS voltage 5.04 and the SIN voltage 0.26
- Broken, my readings were: COS voltage 2.5 and SIN voltage 1.7
I performed the test that toolman outlined by pushing on the solder joint and after I pushed, my readings went to the correct value as outlined above. This confirmed that I had a broken solder joint. The affected joint was IC1 pin10. (This instruction was initially confusing, until I saw that the circuit board was adequately labeled).
To repair, as stated by toolman, I use my solder iron and melt the epoxy, which crumbles up and falls off easily. You do not need to do the entire epoxy. Just remove enough from the affected pin on the IC affected. You then melt the solder and re-solder the connecting pin (being careful to not put too much solder, which would cause you to bridge the small gap between the adjoining pins).

I reassemble everything and my speedo is now working beautifully, and best of all, it cost me $0

Last edited by professorman; Jan 16, 2014 at 09:13 AM.

Jan 9, 2014 | 05:54 PM

holmesnmanny

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Re: Speedometer sometimes jumps to 20MPH and stays there

You need to get a copy of your service manual and follow the wiring to see where it goes. Sounds like you either knocked a wire intermittently loose or a ground is loose now.

The next time your speedometer isn't reading correctly try to put the cruise control on, provided you have cruise control. If it doesn't work then the issue is on the cluster side of the speed sensor wiring as the speed sensor supplies both the ecu and the cluster.

Jan 10, 2014 | 06:49 AM

professorman

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Re: Speedometer sometimes jumps to 20MPH and stays there

Quote:

Originally Posted by holmesnmanny

The next time your speedometer isn't reading correctly try to put the cruise control on, provided you have cruise control. If it doesn't work then the issue is on the cluster side of the speed sensor wiring as the speed sensor supplies both the ecu and the cluster.

Thanks. I will check the cruise control.

Jan 10, 2014 | 06:54 AM

ej7attack

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From: central ohio

Re: Speedometer sometimes jumps to 20MPH and stays there

had this very issue. its a cracked solder joint in the speedo assembly. I had the very same issue. a member named toolman hit the nail right on the head for me with this. check this out.

https://honda-tech.com/forums/showthread.php?t=3175819
.
doing this fixed my problem... and has been problem free since that thread.

Jan 10, 2014 | 06:58 AM

professorman

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Re: Speedometer sometimes jumps to 20MPH and stays there

Quote:

Originally Posted by ej7attack

Awesome. Thanks. Do you have the post from toolman that I can refer to?

Jan 10, 2014 | 07:06 AM

ej7attack

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From: central ohio

Re: Speedometer sometimes jumps to 20MPH and stays there

its around somewhere. don't mean to seem lazy but it took me half an hour to find it before! lol

Jan 10, 2014 | 07:21 AM

professorman

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Re: Speedometer sometimes jumps to 20MPH and stays there

Quote:

Originally Posted by ej7attack

its around somewhere. don't mean to seem lazy but it took me half an hour to find it before! lol

Ha, thanks. https://honda-tech.com/forums/showthread.php?t=2184891

Last edited by professorman; Jan 11, 2014 at 01:01 AM.

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Jan 10, 2014 | 02:54 PM

professorman

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Re: Speedometer sometimes jumps to 20MPH and stays there

Quote:

Originally Posted by holmesnmanny

My cruise control does work. Is there a way to check if the signal is getting to the speedometer properly?

I dont want to start pulling apart the speedo internals if the signal got lost before it go to the speedo.

Jan 10, 2014 | 11:11 PM

holmesnmanny

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Re: Speedometer sometimes jumps to 20MPH and stays there

The fact that it's actually working should tell you it's getting a signal. I would guesstimate that it needs to be resoldered.

Jan 11, 2014 | 05:09 AM

#10

ej7attack

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From: central ohio

Re: Speedometer sometimes jumps to 20MPH and stays there

Quote:

Originally Posted by professorman

Ha, thanks. https://honda-tech.com/forums/showthread.php?t=2184891

let us know the outcome!

Jan 16, 2014 | 08:39 AM

#11

professorman

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Re: Speedometer sometimes jumps to 20MPH and stays there

Quote:

Originally Posted by ej7attack

let us know the outcome!

I want to give a special thanks to members toolman and ej7attack.

I decided to first check my VSS sensor by unplugging it, then check my speedo if I had the same problem, which I did, so I now knew that it was definitely the speedo.

I will edit the first tread to write my notes. Thanks a lot guys!

Jan 16, 2014 | 10:09 AM

#12

ej7attack

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From: central ohio

Re: Speedometer sometimes jumps to 20MPH and stays there

Quote:

Originally Posted by professorman

I want to give a special thanks to members toolman and ej7attack.

no problem man and thanks for the feedback! im glad it worked for you.

Jan 17, 2014 | 05:40 PM

#13

professorman

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Re: Speedometer sometimes jumps to 20MPH and stays there

Uuuugggghhh. My odometer is not working now. It went to 29miles on the trip meter and got stuck. It is stuck at 273999. I am thinking something is physically wrong since it got stuck on the 9 digit.

Any suggestions?

Jan 17, 2014 | 07:25 PM

#14

holmesnmanny

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im guessing the odometer works off of the speedometer ... make sure the speed sensor connector is plugged in all the way

Jan 17, 2014 | 07:44 PM

#15

professorman

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Re: Speedometer sometimes jumps to 20MPH and stays there

The speedometer works now. It turned out that it was my maintenance reset button. I have reset my maintenance indicator before and my odometer got stuck. I pushed the key on the notch and shake it around a few times. It started wroking again.

Mar 18, 2014 | 08:13 PM

#16

Honda_Dude84

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From: Maryland

Re: Speedometer sometimes jumps to 20MPH and stays there

Can some one help me please ASAP. Attached is a video of what my speedometer is doing. I disconnected the VSS and it still did it. I took my 1998 Honda Civic DX to autozone and got a P0705. would that cause my speedometer to do this?

https://www.facebook.com/photo.php?v...73674221995654

Mar 19, 2014 | 12:57 PM

#17

professorman

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Re: Speedometer sometimes jumps to 20MPH and stays there

Quote:

Originally Posted by Honda_Dude84

It looks to be the EXACT same problem that everyone has. Read the tread for the fix. If you are not tech savy, you could just go to a junk yard and get a speedo circuit board. I did my fix with the soldering iron and hot glue.

Mar 19, 2014 | 05:30 PM

#18

BOOM_FIST

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From: Southern Maryland

Re: Speedometer sometimes jumps to 20MPH and stays there

The solder trick isn't hard at all. It took me forever to figure this out as well but since I've resoldered the speedo board it hasn't failed on me yet. I got another from a junkyard for cheap and did that one too just in case, but haven't needed it.

Mar 22, 2014 | 04:21 PM

#19

Honda_Dude84

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From: Maryland

Re: Speedometer sometimes jumps to 20MPH and stays there

Thanks I appreciate it :-)

Mar 22, 2014 | 08:10 PM

#20

honda_lx

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From: Kansas City, MO

Re: Speedometer sometimes jumps to 20MPH and stays there

I don't know if it's Honda's or just older used cars but there soldering likes to fail routinely. I had a driver's master control window switch that I replaced because the contacts points on the solder cracked.

If your driver's side window ever stops going up check out the switch first and look for any cracks in the solder. This is such a common failure I'm surprised it doesn't have a service bulletin or something(Along with speedo issue going in & out). Although I'm not sure the type of failures that warrant a service bulletin.

Mar 22, 2014 | 10:52 PM

#21

Honda_Dude84

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From: Maryland

Re: Speedometer sometimes jumps to 20MPH and stays there

Thanks for all your help

I will try to fix it my self Im just afraid to mess with delicate instrumentation like that. Especially since it's connected to the odometer etc. and thats gone out as well. Once the weather gets warm I will pull the whole cluster.