Speedometer quit

[SDrake]

I just bought the 2003 in my sig. The next day I noticed the speedometer randomly pulsing the equivalent of 3 to 5 mph off zero while idling the engine but while driving it seem steady and accurate. I went through a car wash that sprays the rocker panels (what else it hit I don't know). When I hit the road I immediately noticed the needle sitting on zero. After a few minutes it started pulsing to somewhere near the speed I estimate I was going and then dropping to zero. Occasionally it would jump way past the speed I was going.

After about half an hour of that pulsing it dropped dead and now several days later it is still dead as a door knob. No cruise, mpg etc



I have ordered factory manuals but they may be more than a week and then I am not confident I will be able to figure this out.



Does the speed sensor in the differential work the same as my 94, hook a ohm meter to it and rotate the tires and observe pulses. I can do that check but then what else, -- I am cluless.

 

[cerberusiam]

Speed is derived from the ABS sensors, processed by the ECU, sent to the cluster controller behind the dash which sets the speedo position. If you have no other codes its probably the cluster controller gone bad.



IIRC, hold in the trip meter button while turning the key on and it should go into a cluster test and show you codes for cluster problems.



If nothing else, its kinda cool to watch the dash go crazy for 15-20 seconds.

 

[Tinman]

This is a little different from my issue. All my gauges would just quit intermittently. It was the $800 TIPM. But a fluctuating speed could be the speed sensor on the diff. Seen a couple of those go bad.

 

[SDrake]

OK so the ABS could be involved. I noticed that there is a sensor of somekind on top of the differential. Is that the ABS sensor for the rear brakes? I figured it might be a speedo sensor. When I picked up the truck the abs light was staying on. Haven't had a moment to check into it yet but have ordered manuals. A day later the odometer quit and also the overhead consol is giving incorrect temps and just stays on what ever temp it comes up with when I turn the key. Probably all related. The truck needs new brake pads so I will start checking out the sensors etc as I get to each wheel. I have a set of manuals on the way.



After I get some of those things out of the way and I still can't fix it where do i take it to get it fixed. The Dodge dealer? I avoid those guys like the plague.



I live in Huntsville, Al but would gladly travel a hundred or two miles to a place where I knew there was a person who knows what he is doing, --- could very well be a dodge dealer.



I am in a dead run with commitments for the rest of this week. Next week I will run codes and start brake job, and report on what i find.



I like learning things but that stuff with the computers I did not want to get involved but here I am involved.

 

[SRadke]

IIRC, hold in the trip meter button while turning the key on and it should go into a cluster test and show you codes for cluster problems.

Do this first, find out if it's a dash problem.



-Scott

 

[TCDiesel]

Try to pull the speed off the OBD Port. . if the tool is showing incorrect speed then its a sensor problem. . if correct speed then check the IC with tool, generally if reseting the IC has correct increments then its good.

 

[SDrake]

Try to pull the speed off the OBD Port. . if the tool is showing incorrect speed then its a sensor problem. . if correct speed then check the IC with tool, generally if reseting the IC has correct increments then its good.

OBD wasn't much use on my 94 and my 2007 Toyota has never hiccuped so I don't have a OBD scanner. I am so swamped with things to do to get this truck going in time for some trips I just don't have time to do much research on scan tools. Can any of you make a recomomendation of one that will take care of the kind of things I am going to need on this 2003 dodge? On I can find on Amazon, Ebay or local parts store. I realize that is a wide range since these things go from a complete laptop with sensors and just basic one that only do limited. What will take care of me on this truck.



I am not ready to get a smarty. Maybe it does not completely operate as a diagnostic scanner anyway.



Tinman I think mine is doing what yours did. My initial description of the problem a little vague. Mine would try to come on for a second or two and then go to zero for a minute or so. The fact that in doing that ocdasionally it would shoot way past the speed i was going suggested more than just a bad connection and I immediately thought of some computer chip being toasted? I need a scanner anyway so I want to read the sensors just to see if they are OK as was suggest.



Sure interesting about using the signal from the front ABS etc



Thanks for all you input. I am going down the same road I went with the 94. If it hadn't been for TDR I would have never been able to keep that truck. The dealer was killing me and doing nothing. He was going to change my injector pump out of warranty when after much frustration I learned on TDR the problem was the fuel return hose, and on and on with stuff like that. TDR got me going with a fantastic truck that I enjoyed to the very last. Right now I miss my 94.

 

[SDrake]

Do this first, find out?! if it's a dash problem.



-Scott

OOPs I didn't think. Don,need scanner to get the codes. I will do this first thing. Thanks

 

[SDrake]

Did the hold trip meter button hold pressed while turning on the key. All the gauges and lights went through a little dance up and down the scale and appeared to be doing what they were supposed to do and then the screen cleared and posted a message C-Code and then cleared and posted 00-00.



I think this means the dash is OK. Does it rule out the TIPM board. I hope this turns out to be a sensor.

 

[TCDiesel]

TIPM relationship to IC is Power ONLY,The IC is totally integrated and receives Messages PCI or J1850. Mostly likely sensor.

 

[SDrake]

Try to pull the speed off the OBD Port. . if the tool is showing incorrect speed then its a sensor problem. . if correct speed then check the IC with tool, generally if reseting the IC has correct increments then its good.

What tool can i use to pull the speed off the OBD port. I looked up DRBIII scanners and whoa ---no go there $$$$thousands.



BTW thanks for the info on the relationship to the TIPM. Also I saw somewhere how to turn the key on three times in a row or something and can read some codes. Where is information about what codes can be read or what this feature can do, certainly less than a scanner but I would like to see if some codes are there.

 

[seafish]

HArbor Freight has decent OBD2 scanners for less then $120... might not be a bad investment. I have one of these and it has worked flawlessly for reading codes on several differevnt vehicles.
This one looks like it may even read the data stream, which is what you want--

CAN OBD II Code Reader/ EOBD Scanner

If it does NOT work to do what you want it too, you can likely return it for a full refund.

PS--click on the reviews in the link above, it looks like a nice product that WILL read and even record the data screen. There are over 30 good excellent reviews for this tool.

 

[SDrake]

HArbor Freight has decent OBD2 scanners for less then $120... might not be a bad investment. I have one of these and it has worked flawlessly for reading codes on several differevnt vehicles.

This one looks like it may even read the data stream, which is what you want--



CAN OBD II Code Reader/ EOBD Scanner



If it does NOT work to do what you want it too, you can likely return it for a full refund.



PS--click on the reviews in the link above, it looks like a nice product that WILL read and even record the data screen. There are over 30 good excellent reviews for this tool.

Looks like a must have. I need to learn what the difference in OBD II and DRBIII



BTW I just did the key off three times and then leave on with out starting and got the Code P0500 which is "Vehicle Speed Sensor Malfunction"



Looks like I need to start hunting up the sensors and figuring out how to test them.

 

[TCDiesel]

It's going to be either the speed sensor on the Transmission ,or the ring gear sensor on the Rear axle housing... My monies are on the ring gear sensor.

 

[SDrake]

Any way to get some indication of whether the thing is working. I seem to recall on my 94 I could disconnect and put an ohmeter across the leads and watch for pulses as you spin the wheel.



Never got into the front abs sensors. How do you test them. Or do you just substitute parts?



I can't find any good shade tree mechanic type stuff in a electronic manual I downloaded. It is all about running the $3K DRBIII scan tool and subing parts.

 

[TCDiesel]

Just pull the sensor form axle housing and check for continuity. When the speed sensor is bad it generally turns on the ABS light.

 

[SDrake]

Do you test front abs sensors the same
way?

 

[TCDiesel]

I see no relationship to the front ABS sensors and speedo,,,If ABS & brake light are on then its possible for poor connection or bad front ABS sensor.

 

[SDrake]

Update on problem

I have been gathering as much informtion as i can. the service manuals are not very encouraging. Do a visual and then hook up to the DRBIII scan tool etc. I am trying to learn the wiring diagrams so that i can think a little more logically but that is an uphill battle.



Yesterday the speedo started working and simultaneously the outside temperature reading in the overhead consol started working.



There must be a common connector or device that is affecting these two together. any ideas what that might be?

Looking at the manuals I notice that the Power Control Module receives input from Ambient Temperature sensing. Is that referring to the sensor in the air breather and is that air breather tempearature sensor the one that supplies the read out for the overhead consol. I sort of expect that the overhead consol would get its signal from a sensor somewhere outside the engine bay.

 

[cerberusiam]

The temp sensor for the overhead is inboard of the driver side headlight bolted to the radiator support. The ECU uses the temp\baro sensor on the air box to source its readings.