Wildly inaccurate speedo and tach readings
#1
Wildly inaccurate speedo and tach readings
The tach and speedo are reading waaay off on cold (36 to 50 degrees) mornings, but not consistently. Sometimes they will read far too high, other times no reading at all. When it's warm and at the end of the day they work normally. Also, the in dash 'compass' reads 180 degrees off and this started after the dealer replaced the FICM.
Any ideas on what I can check before I take it to the dealer and spend large amounts of money?
I haven't posted in awhile. I hope all is well with everybody!
Any ideas on what I can check before I take it to the dealer and spend large amounts of money?
I haven't posted in awhile. I hope all is well with everybody!
#2
Check the connection to the instrument panel:
A) critically, beside the brake where it connects.
Clean all contacts, esp of fuse and if there is a relay, check the panel power relay. Clean all contacts with circuit cleaner.
Be sure both wiring harnesses are disconnected and contacts inspected and cleaned.
Grease it with dielectric grease.
Make sure there is no road salt or other stuff that may have crudded up the connections.
B) If this doesn't work, R&R instrument panel and clean the contacts where 2 harnesses attaches to panel and grease the contacts.
While you are at it, replace any old bulbs / dead bulbs. They are probably no. 73 and No. 37 bulbs.. about 5 each.
See my thread on electrical problems.
C) Tach / Speedo
The common factor between those is the connector to the engine .... you may need to check the connection there as well as above.
Infact, I would do this first.
It sounds like bad contacts...
Ford is real bad with corrosion of electrical contacts where I am.
A) critically, beside the brake where it connects.
Clean all contacts, esp of fuse and if there is a relay, check the panel power relay. Clean all contacts with circuit cleaner.
Be sure both wiring harnesses are disconnected and contacts inspected and cleaned.
Grease it with dielectric grease.
Make sure there is no road salt or other stuff that may have crudded up the connections.
B) If this doesn't work, R&R instrument panel and clean the contacts where 2 harnesses attaches to panel and grease the contacts.
While you are at it, replace any old bulbs / dead bulbs. They are probably no. 73 and No. 37 bulbs.. about 5 each.
See my thread on electrical problems.
C) Tach / Speedo
The common factor between those is the connector to the engine .... you may need to check the connection there as well as above.
Infact, I would do this first.
It sounds like bad contacts...
Ford is real bad with corrosion of electrical contacts where I am.
#3
welcome to the club! mine just started doing that too...from what I have read this is a known problem and I think there is even a TSB on this, replacing the cluster is fords fix...but someone here mentioned that the cluster was $500 and the dealer had to program it for you for an additonal cost...OUCH!! guess i'm living with a bad speedo/tach unless gearloose's idea fixes it...
mine started with the tach acting funny now the speedo has started it...
gearloose1 - I will try what you have suggested!! thanks!
Does anyone know if the cluster can be fixed? maybe by an electronics repair shop? thats gotta be cheaper than a new one.
mine started with the tach acting funny now the speedo has started it...
gearloose1 - I will try what you have suggested!! thanks!
Does anyone know if the cluster can be fixed? maybe by an electronics repair shop? thats gotta be cheaper than a new one.
#4
Thanks!
Hey, being in the electronics business, I can tell you that most electronic modules (without mechanical things like relays) just either work, or not.
99% of the issues are caused by the connections / wiring to the outside.
Everything about your condition:
- isolation to 2 gauges that connect to engine via a common harness
- intermittent
Suggest it is cabling / hookup from engine to the panel that is the problem: NOT the panel itself.
You can replace the panel, but I suspect it might not solve your problem (with the exception that the very act of replacing the panel mean you jiggle the 2 connectors on top, and by doing so, may just clean up the contacts enough IF it is those 2, and not other connectors that is the trouble.
I strongly advise you try cleaning contacts at the footwell, esp. where the engine (FICM?, Engine computer) sends its RPM / SPEED signal to the panel.
That is where you are going to find the bug.
The only exception I can think of to my rule is back then, there was an issue that caused gremlins caused by the switch to non-lead solder.
There were issues with bad solder joints, whiskering (dendrites growing from one lead to next) that CAN produce the intermittent symptoms you mentioned --- but that is rare. On that condition, the fix is to replace the panel.
The repair for the above involve opening the panel, and checking for bad joints, whiskers... conductive dust, etc...
So there you have it... good luck.
Here is the link to the battery / alternator / ABS light issue.
https://www.ford-trucks.com/forums/9...on-issues.html
#6
If you have an oscilloscope, hook it up to the signal wires for the RMP and Speedo.
Then see what signals it is sending when it failes.. vs normal.
Then work backward from the wire back to track the source.
Labor intensive.. but it will do it.
Cheap way:
Use an ohm meter (while it is unplugged) to test the resistance of the wires all the way back to the origin of the signal.
Less accurate, a test lamp.
Look for a break, bad connection.
Good luck.
#7
The tach and speedo are reading waaay off on cold (36 to 50 degrees) mornings, but not consistently. Sometimes they will read far too high, other times no reading at all. When it's warm and at the end of the day they work normally. Also, the in dash 'compass' reads 180 degrees off and this started after the dealer replaced the FICM.
Any ideas on what I can check before I take it to the dealer and spend large amounts of money?
I haven't posted in awhile. I hope all is well with everybody!
Any ideas on what I can check before I take it to the dealer and spend large amounts of money?
I haven't posted in awhile. I hope all is well with everybody!
Also - there is in fact a TSB on this:
TSB 07-11-2 : STUCK OR JUMPING / BOUNCING / ERRATIC SPEEDOMETER AND/OR TACHOMETER
I have sent it to you (assuming the roadrunner email address I have is still good).
........ Edit - Email address is not valid anymore ........
Some of the TSB:
For a speedometer related concern, If no DTCs are present, the issue may be with any of the following components:
Cluster
ABS Module
ABS Speed Sensor
Vehicle Wiring
If the symptom is a continuous (non-intermittent) large inaccuracy, ensure that the axle ratio and tire size are properly configured in the ABS module.
Cluster Concern
A known issue exists on the instrument cluster where it is possible for the graphics applique to separate from the cluster backplate and interfere with pointer operation. The suspect vehicle build months are July, 2005 to January, 2006. Although not impossible, vehicles built outside of this time period will likely not have this issue. The most common symptom is the speedometer pointer sticking while operating in cool or cold weather and the vehicle interior is beginning to warm up after a cold start. Revised instrument clusters are now available for service that includes a fix for this concern.
To identify the cluster as the root cause:
Monitor the vehicle speed sensor (VSS) PID in the powertrain control module (PCM), and the speedometer needle position while stopped.
If the speedometer displays 5 MPH (8 Km/h) or more, and the VSS PID indicates zero, replace the instrument cluster.
With an assistant observing the diagnostic tool, drive the vehicle at 20, 40, and 60 MPH (32, 64, and 97 Km/h) as indicated on the diagnostic tool, and record the value indicated by the speedometer.
If the speed indicated on the diagnostic tool versus speedometer readings vary by more than ± 5 MPH, (8 Km/h) replace the instrument cluster.
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#8
bismc
Based on the problem description, it is more than likely to be this issue described in the TSB than a bad contact issue.
The giveaway is that nothing else is wrong, whereas in my cases, it is everything else screwing up.
The sad part is, the TSB problem mean a new cluster.. real $$$ to fix.
If you are replacing the cluster, ensure the new one has new bulbs in it -- do it while it is out.
It also doesn't hurt to clean the contacts of the old harness, and grease the contacts to prevent corrosion.
Good for 5 or 6 years (or the next owner).
#11
[quote=bismic;8249485]Sorry that you are having some issues Russ ..... but it is good to see you "posting".
Also - there is in fact a TSB on this:
TSB 07-11-2 : STUCK OR JUMPING / BOUNCING / ERRATIC SPEEDOMETER AND/OR TACHOMETER
I have sent it to you (assuming the roadrunner email address I have is still good).
........ Edit - Email address is not valid anymore ........
Hey Mark,
I pm'd you my updated email addy. Thanks for checking on this and for caring! You still Da Man!!
Looks like this truck is going to absorb even more cash.... again.
Thanks for the responses and great advice guys.
Also - there is in fact a TSB on this:
TSB 07-11-2 : STUCK OR JUMPING / BOUNCING / ERRATIC SPEEDOMETER AND/OR TACHOMETER
I have sent it to you (assuming the roadrunner email address I have is still good).
........ Edit - Email address is not valid anymore ........
Hey Mark,
I pm'd you my updated email addy. Thanks for checking on this and for caring! You still Da Man!!
Looks like this truck is going to absorb even more cash.... again.
Thanks for the responses and great advice guys.
#12
#13
#14
Once the new unit was installed, I never had another issue. When the temperatures would drop the speedometer would show that I was driving like 90 mph while actually driving approximately 35 or so. And sometimes it would show I was driving 30 or so when I was watching telephone poles blur by out my driver's window.
#15
I had my cluster out... it is not "sealed" and yes, dust did get into it...
Could it be that the Ford tech meant that the speedo / tach gauge mechanism (which is sealed) got contaminated?
I actually cleaned the contacts / dust out of mine where it is not sealed.
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screaminford
Clutch, Transmission, Differential, Axle & Transfer Case
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01-24-2011 09:29 AM