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No Speedo - ABS light

30K views 17 replies 10 participants last post by  AllOut0606 
#1 ·
So i took my truck to local retards aka my sh**ty ford dealer (not saying all ford dealers are bad) and after paying the $90 they came to the conclusion that the cause for no speedo, odometer, ABS light, and flashing OverDrive light was caused by a faulty GEM. So i bought the GEM and put it in tonight. After 4 hours of painstaking work, i replaced the GEM. It would have been faster, but i was using an allen key instead of a star key to get the screws holding it out. Cleaned up and took it for a spin. The new GEM did absolutly f***ing nothing. I'm pissed.

Is there something other then a GEM or rear speed sensor that could be causing this annoying and expensive problem?

Symptoms - No Speedometer, No odometer, Flashing OD light, and ABS light - which means my ABS isnt working. Cuz i went sideways trying to stop in the rain last night.

PLEASE HELP!!
 
#3 ·
It's just a late-night, wine-addled guess, but here goes . . .

It's probably the VSS which resides in your differential housing. Much cheaper (and easier to get to :sofa ) than the GEM, or another sensor (ABS sensor?).

Hie thyself to the local PSD guru who has AE or an NGS scanner and see if that person can help you.

I've replaced both the GEM and the VSS on my truck. When the GEM failed, I couldn't even start my truck. I don't remember precisely the VSS symptoms, but I do remember the Speedometer not working.

Wish you well.

prt
 
#4 ·
plainredtruck said:
It's just a late-night, wine-addled guess, but here goes . . .

It's probably the VSS which resides in your differential housing. Much cheaper (and easier to get to :sofa ) than the GEM, or another sensor (ABS sensor?).

Hie thyself to the local PSD guru who has AE or an NGS scanner and see if that person can help you.

I've replaced both the GEM and the VSS on my truck. When the GEM failed, I couldn't even start my truck. I don't remember precisely the VSS symptoms, but I do remember the Speedometer not working.

Wish you well.

prt


how does one get to the VSS and what does that stand for?


GEM = General Electronics Module
 
#5 ·
The VSS (vehicle speed sensor) is located on top of the rear differential. I believe there is 1 10mm bolt that holds it in place. When the VSS goes out you loose your speedo, abs, the SES light comes on. . .all symptoms you are describing. They are very easy to replace. . .and are basically cps's so are very commonly failing parts on our trucks. . .but i don't think they're too pricey, i can't remember, brian replaced mine w/my tranny. . .guess you could say i paid 4300 for mine, and he threw a tranny in for free LOL . Sorry, it's late, i'm going to bed now. Let us know if that works for you.
 
#6 ·
i have replaced two of VSS, i didnt know what you were talking about because i call it a rear speed sensor. i tried replacing those before i bought the GEM. It didnt fix the problem. Thanks for the input everyone.

Any other things causing this?
 
#7 ·
Check your wiring going to the VSS. There should be two wires, and sometimes they get corroded at the frame. I will try to explain to the best I can. "USUALLY" we see this corrosion right where the wiring comes off of the frame and starts its journey down to the VSS. it is around the shock area I believe. Also check the plug at the VSS, Sometimes there is corrosion there also.
 
#8 ·
No sense in guessing...It requires meters and probes to check everything it could be...Without being there to assist, I'd highly recommend you visit your local library and hit the better manuals they carry...Usually they will print the info you need at a nominal price and save you the migrain....It could be anything from corrosion to 1 of numerous grounds...Read the proper section and you will get some excellant tips...
 
#9 ·
No one is guessing here. We are all making suggestions that we have seen in the past with our own trucks or others, that have had the same issue. I am not against going to the library, but common sense tells me that If he checks for the problems that we have all stated at least he will have a good starting point if we are all wrong.
 
#10 ·
I'm not trying to offend anyone...Not knowing all the circumstances of available tooling and experience,and knowing if he looks at a wiring schematic, he will see all the places that issues could and will arise.. You are absolutely right, they are all good starting places...
 
#11 ·
UnlimitedDiesel said:
Check your wiring going to the VSS. There should be two wires, and sometimes they get corroded at the frame. I will try to explain to the best I can. "USUALLY" we see this corrosion right where the wiring comes off of the frame and starts its journey down to the VSS. it is around the shock area I believe. Also check the plug at the VSS, Sometimes there is corrosion there also.
i appreciate all the input. I have checked the VSS connections, but i am going to look into the short along the frame.

Also, i called the ford dealer and they are going to re-access the situation for FREE. But they said the GEM might need programming. That doesnt sound right, but we shall see.

Thanks again.
 
#13 ·
I got a GEM / dealer story that's real similar, only I knew exactly what the problem was going into it. I just didn't have the time to deal with it (and some other problems at the time). My parking brake switch was a bit corroded and I told the dealer service I wanted it removed and either cleaned up or replaced. I got a call a few hours later telling me I needed a new GEM. I told them to bite off -- I got home and removed and cleaned the switch myself. Works like a champ. Nothing at all wrong with the GEM. When you guys run into this crap it's probably worth while to send a short note to the dealership general manager. Too many service shop managers are either in it for the $cam, or are just too dumb to engineer their way out of a wet paper sack.
 
#14 ·
could it be the gauge cluster itself?? or wiring to the gauge cluster?
 
#15 ·
my truck started doing this exact same thing on Saturday. I dont know if I'll have time before Thursday to replace the VSS and I'm leaving to go race out of town (50 miles away) for 3 days, is this going to be anything to worry about until next week?

ABS light is on all the time, speedo doesnt start working until I get up to 30-35 mph from there on it seems to be fine. Truck doesn't act any different except for those two issues.

The SES light is not on and I cannot determine if the OD light is flashing, the end of the shifter that goes around the button disappeared and that OD light doesn't work most of the time.
 
#18 ·
96 stroker said:
not to be a smart a** but could it be the fuse or a bad ground or short in a wire?

your probably right, but i have not tried to chase the wire, because it hooks up with 20 other wires, heads towards the engine compartment, and i loose it.

you know, i think i can hear my pads starting to wear down and the scrape you get from that. i'm thinking it could be time for new pads, also causing the problem?

sometimes when it is very humid, or rainy, the light wont turn, everything is fine. does that help? thats why it cant be a fuse, it works too much. i am thinking short, or the brake pads in the front.
 
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