Speedo issues

[dpuckett]

This is the first non-gear related speedo issue I've had with the 92. Mom borrowed it last week while (coincidentally) I fixed her speedometer. Now, I can hit about 45mph in neutral with a blip of the throttle. I'll be able to hit 20mpg now, but I'd still like to know where to start. VSS? What side of the wiring should I look at? Is this a sign of a bad PCM? I'd think the problem is in the wiring, possibly grounding out on something.



Daniel

 

[hotram03]

Daniel I would start at the VSS, sounds like the culprit. Dont forget to do a wiggle test on the wiring as well, if VSS checks ok, check wires going to actual VSS for resistance, check resistance to ground, good luck.

 

[Philip]

Check your grounds Daniel. With the vehicle not moving the VSS is out of the loop. Your speedo is getting a stray power reading from somewhere.



The dash ground are located behind the lower right side panel. Thats the panel the cargo light switch is mounted in.

 

[dpuckett]

Thanks, guys. I was thinking along the same lines, just needed some reassurance that I was on the right track.



DP

 

[JGrefenstette]

daniel,

since i bought my truck in may ive had speedo issues. mine will randomly go out, but never while im moving, i will happen at idle, or just never come on when i first start out. for insince, it likes to stop working after going down bumpy roads then idleing. i was acctually able to trace it to wireing i think, because for the last week or so, every time it dosent work, i just jiggle the wire comming from the t-case, and it comes back every time.



just my thoughts

 

[cerberusiam]

Well, this is a disappointing!





From the title I thought Daniel had questions about the new TDR beach wear. :-laf:-laf

 

[Philip]

I thought Daniel had questions about the new TDR beach wear

Oh you just had to go and say it. Now here comes Pete. :-laf:-laf

 

[MMeier]

Well, this is a disappointing!





From the title I thought Daniel had questions about the new TDR beach wear. :-laf:-laf

Oh no!! Speedos???... . TDR beach wear???... . most of you guys???... =

 

[JLEONARD]

From the title I thought Daniel had questions about the new TDR beach wear

I was thinking he was having trouble.....

oh never mind.

 

[Moab4x4]

I agree with all the posts on grounds or loose wires.

If all that fails, I would suspect the speedometer (I think I will avoid shorthand around here today :-laf) head before the PCM.

From what I have been able to deduce, the PCM supplies the DC reference voltage to the VSS and the speedometer head and then the VSS chopped signal indicating speed is then sent to the head and the PCM NOT to the PCM and THEN the speedometer head.

I had my Speedometer head working for a while without the PCM involved by supplying voltage to the supply side of the VSS myself, but things still kept degrading until I was doing 100 on main street. (Oh I wish) I suspect my Speedometer head was on its way out the whole time.



If anyone can correct this or add more details, please do.



My speedometer electrical research ended when I got the 84k miles parts truck with all good pieces and I replaced everything during the rebuild.



I hope its one of the easy fixes.

Ken

 

[Ncostello]

I've just encountered some speedo issues this past week. Slowing down on the highway to make a turn... hit my right turn signal and the speedometer jumped or spiked up and has been erratic since.



Seems like now it won't register anything or kinda like a cable is broke and only hits and misses causing the needle to jump.



Is my "91. 5" cable or computer controlled? Guess I could always crawl under there and look for a cable .

 

[dpuckett]

Ncostello- your speedometer is definitely electrical, unless it has been replaced by someone along the way.



The rest of you- I have not done enough ab workouts to enjoy the privelege of said "beach wear. " I'm still at the baggy swim trunks and t-shirt stage. The hot weather will take some of the flub off, though.



cerberusiam- are there really ANY TDR members who qualify to wear that? Not many, would be my guess.

DP

 

[PToombs]

Oh you just had to go and say it. Now here comes Pete. :-laf:-laf

Believe it or not, I'm going there! :-laf

 

[cerberusiam]

From the title I thought Daniel had questions about the new TDR beach wear

I was thinking he was having trouble.....

oh never mind.

I just wanted to make sure he got the "Got Boost?" logo on the CORRECT side, ya know.

 

[JGrefenstette]

Ncostello- your speedometer is definitely electrical, unless it has been replaced by someone along the way.



The rest of you- I have not done enough ab workouts to enjoy the privelege of said "beach wear. " I'm still at the baggy swim trunks and t-shirt stage. The hot weather will take some of the flub off, though.



cerberusiam- are there really ANY TDR members who qualify to wear that? Not many, would be my guess.

DP

haha,

well daniel... i might qualify to wear it, but i wouldnt be caught dead in one, so it doesent really matter anyhow.



the only reason i thinki qualify is cause i only 17 and havent started the down hill slide yet :-laf

 

[cerberusiam]

cerberusiam- are there really ANY TDR members who qualify to wear that... . DP

... without getting slapped with obscenity charges, ya mean? :-laf:-laf

 

[PToombs]

the only reason i thinki qualify is cause i only 17 and havent started the down hill slide yet :-laf

OUCH! That's gonna leave a mark Daniel! :-laf

 

[MMeier]

the only reason i thinki qualify is cause i only 17 and havent started the down hill slide yet :-laf

If you 're associating with this bunch, trust me, you ARE on the downhill silde!!

 

[TWorline]

I just wanted to make sure he got the "Got Boost?" logo on the CORRECT side, ya know.

Good one!:-laf:-laf:-laf:-laf

 

[JGrefenstette]

If you 're associating with this bunch, trust me, you ARE on the downhill silde!!

haha,



well i proudly associate myself with this group, and if that means that the downhill slide already started, so be it. id say its well worth it