Electrical specialists....HELP!!!

[BushWakr - RIP]

Electrical specialists....HELP PLEASE!!!

Well guys, if it ain't one thing it's another... . While trying to get the final arrangements made and completed I have hit an electrical problem with the truck. Since I really suck at this type of thing I thought I'd call on some brain power in here.....



My speedo has taken to reading what ever the heck it likes... . in fact with just the key in the "on" position the speedo, after a few seconds, will slowly climb from zero to 40 or 50 Kph and stop/hold there... . and that's before I even start the thing.

I also noticed that after driving for a while it seems to settle down and behave relatively normally...



So far, I have:



>Checked all the connections under the hood and on the transmission with the key on.

>Disconnected the speed sensor and most of the sensor connections under the hood with the key on

>Tried disconnecting the battery for a while.



I've run the codes and I got the following:

> 32, 35 or 45 and 55 (end codes)

>12 and 55 (end codes)



This is just in the last couple days or so now... .

I have taken apart a speed sensor and if you guys saw what was in the old one I took apart you'd bring a gun to the parts counter as self defence... . the markup margin must be 1000% I kid you not. .



Anyway, can anyone figure out why the thing would actually read a speed while not even running???



Thanks guys... .



pastor bob...



>edit: I have added this part after Stan has posted... .



>When I turn the key on the speedo will sit for a few seconds then slowly rise.

When I disconnected the majority of connectors (speed sensor etc) the speedo needle still reads as though the vehicle was moving at speed... .

What can supply a signal to the speedo with only the key on ??? It's really wierd because after the truck has been run for a bit, it seems that the speedo settles down and behaves fairly normal... it will occasionally twitch but it really acts like a connection is bad, or the "warmth" of the engine running eases or reduces the problem/dries something out ... ?? if it dries something out it should stay dried out right. . ??

As for the speed sensor, I took apart an old one I had. The one on the truck is about 1 year old, and even unplugged with the key on the speedo is still reading a value...

I haven't been fiddling with the wires related to the dash and I have not had any other odd electrical problems that coincide with this either... .

I really hate to part with $90 Can. for another sensor. .

 

[paccool]

Bob, sorry to hear about the truck problem on top of the other things going on.

I just spent about 45 minutes looking at the manual trying to see where there might be a problem. It looks to me like it is either in the speed sensor, the wiring from the sensor to the speedometer, or the speedo itself. You said you took the sensor apart, did you replace it or did it check out OK?



The first thing I would try would be the sensor but it sounds like you have already done the things I would try. Does Mark still have his wrecked truck? If so, talk him out of the gauge cluster and swap it out to see if that cures the problem.



Anyone else have any ideas? Come on guys, the Pastor has helped lots of us, lets try to return the favor.

 

[Paychk]

PB



Try unplugging the DRL module and see if it is feeding a signal into the speedo. Next I would unplug the gray connector (10 pins inside) at the rear of the engine between the brake booster & the intake manifold and see if that has any effect. If no, then the speedo is picking up pulses from some where (all it does is count pulse from the sensor, the computer doesn't drive it). All you can do is break the electrical connectors until it stops, if it doesn't stop, I would try a spare speedo and see what that does.

 

[BushWakr - RIP]

Uhhhh... in keeping with my spectacular ineptitude regarding electrics' ... what is a DLR module???



pb...



edit: oops, sorry it should be DRL module... good catch paychk

 

[Paychk]

It should be DRL, which is the Daytime Running Light module, the thing that makes your headlight come on in the daytime.

 

[Paychk]

Located in the engine compartment, left side somewhere.

 

[Paychk]

https://www.turbodieselregister.com/forums/attachment.php?attachmentid=48353&stc=1

 

[Paychk]

#ad

 

[CGauthier]

Bob, I nearly went into a coma thinking about your problem-but I have to believe it is the speedo itself... . not that I'm an electrical scientist or anything, but the speedo works based on switching on and off... even with a bad connection there's no way it would switch on and off that much to make your speedo to even register. I believe you have the three wire vss, which is a little greek to me what the third wire is for, probably to control OD or something like that... anyone know what happens if you send the 8 volts straight to the speedo... i. e. jumpering from the the two wires together? I lent my truck to a buddy who's moving-otherwise I'd try it, but I don't think it would make the speedo behave that way... but who knows. If a working speedo doesn't register anything or goes all the way to the top when supplied with power I'd bet big dollars that it's the gage itself. I know, alot of gibberish for a guy who doesn't know what he's talking about lol. The weird thing is tho, that I wouldn't think power should be getting to the speedo at all without the vss. Only other thing maybe from the pcm? But I thought I read somewhere here that the pcm didn't control the speedo?



Paychk-that test with the ohmeter, can that be done the same way with the three wire vss? I tried zoning into that schematic you posted earlier... I think it sent me back into that coma lol.



Hey Bob, maybe the truck is tryin to tell ya something drive faster! Lol







Carl G

 

[Philip]

You could be getting feed back from a bad dash ground. It could cause the problem your talking about. Your dash grounds are located behind the OD switch. Drop your center panel under the column and look behind the OD switch. You can see the grounds. There are three wires mounted to the metal dash support. Remove the 1/4" head screw and sand that metal support and the terminal ends. Then reinstall.



Also do the body ground out on the raditor support.



Then see if the speedo does the same thing.

 

[Paychk]

I just know realized that this may be a 3 wire VSS, the continuity check should also work for this system. In addition there should be 8 volts on the tan/yellow stripe wire. I would try disconnecting that gray connecter and check it, the input for the tach flows through there too, maybe it is shorting out and feeding into the speedo?

 

[BushWakr - RIP]

I'm going out today to try some of this stuff guys... . if you have any other ideas please post them...

In my case it is a 2 wire VSS... this is used on either the manual G360 trans and/or a 4X4 with NP205 case... that is me.

I'll have a wack at the grounds... that sounds like it has some promise.

Don't give up on it yet though... I'll post results between tinkering and family arrangements as I'm able. .



thanks guys. .

pb.

 

[jdurham]

Hey Bush,



I have and extra instrument cluster I'll send you to try out if you like, just pm your address. Oh, they do have mail service up there, don't they????



Jim

 

[BushWakr - RIP]

Hi Jim,



Hey man that's a great offer... I'd like to make sure I have covered all the bases before we go to that step, but I'm very appreciative of the offer. .



Well, I was under the hood/dash most of the day...

I checked pretty much all the connections/grounds/solenoids w/connectors etc. .

No matter what I plugged in or unplugged it seems to make no difference.

The speedo will slowly begin to rise and then hang around 45-50 Kph.

I've never seen anything like it...

Last year when the speed sensor went out, it would be normal until I was moving, then it would twitch and jump. Also, at that time, it didn't matter how long I drove the speedo was still twitchy... unlike now.

Now it starts rising and then twitches once I'm moving and slowly seems to settle down after a while of driving... .

Damn thing is hauted !! ... ... . ahhh crap I gotta send myself a warning about the language...

Hey Carl... I know EXACTLTY what you mean about going into a coma on this stuff... I'm there with ya bud... darn wires and crap. .



Ok so I don't were to go from here... . I've looked at the wiring diagrams in the FSM and I don't see ANYTHING that could be feeding back to the speedo...

The FSM does say that the speedo is powered/fed by the vehicle distance sensor (speed sensor)... but if I unplug that it still doesn't eliminate the speedo problem.



Were do I go from here... ????



pastor bob... doing penance for foul language...

 

[CGauthier]

Pastor... . I'm willing to bet alot on your speedo. Reason being that it actually settles down and actually works while driving, which means the circuit that reads the pulses and all that is functioning... . if you have a short or a bad connection it really shouldn't work properly while driving with all the bumps and movement. Combined with the fact that the guage itself should not come up at all, whether there is constant power or not; heck if one of the switches in the vss is making contact to complete the circuit when we park we would get those symptoms too. I can't see it any other way... . I am so sure of this that if you change the cluster and it doesn't fix the problem I will help pay for it



Carl G

 

[JMariotti]

Maybe your truck is just so fast it thinks it's moving when it's standing still ;0)

 

[dpuckett]

Ditto what Carl said, except the offer to help pay for it. Though I had the VSS out on my 91 when I got it, and it would jump when sitting still at a light. SOmetimes went up to 60-70mph, though it was still twitchy. Never did settle out and act right, till I got a new VSS. You got O'Reilley's up there? I have an idea I can PM you if you do.



Daniel

 

[BushWakr - RIP]

"..... Maybe your truck is just so fast it thinks it's moving when it's standing still



ROFLMAO !!! :-laf :-laf..... you're probably right bud... .



I'll gladly hold the offers of assistance in reserve guys... you never cease to amaze me in here... . daft bunch that you are. .



Here's a twist on the story... today when I got into the old girl, I turned the key and waited for the speedo to get a head start on my drive to the shop... . low and behold, no more problem... darned if I know what's going on.

Maybe it got scared yesterday when I started yanking out wires and disconnected switches... maybe not.

Today it did not act up once... although I did have a slightly related problem... . my trans temp read 200*F within 5 minutes of start up... . now that one I got cased out...

The male/female plug gets kinda "iffy" at times and a good wiggle and cussing fixed it in short order.



So, at the present time I seem to be back on the road to okey dokey status..... I think it knew that I was calling in the troops and quietly gave in... Mhmmmm... ya right!



I will keep my options open on this one though guys... I really appreciate the offers of help and I'll do some snooping to see if we've got some O'Reilley's up here.

I've given up wine women and song... . wine is nasty, women. . well I'm a 31 year veteran of marital combat errrrrr bliss, and if you've ever heard me sing you'd understand my giving that up :-laf :-laf



Well, thank you for the help and I admit the ideas ALL were a big help. Thanks for the support guys. . I won't forget it.



pastor bob... putting in a good word for the 1st Gen crew.

 

[CGauthier]

Glad your up and runnin' bud... and it didn't cost you(or me) nuthin Now hopefully it stays that way... it probably will because I think that horse is giving ya some respect now :-laf



Carl G