Sigh... P0500 and dead speedo...

[Red Devil]

'98 SHO (anyone surprised?) ~80K miles on it.

Speedo would work on and off then just die. o/d would flash on and off and the MIL would go off (and once the speedo dropped I got the fun shifting of a tranny with conflicting signals).
-Pulled the code and got a P0500 (Listed as VSS sensor "A").
-No abs light. Solid or flashing, lamp works.
-When datalogged there was no report of speed on the log/computer when the problem occured either.
-When in cruise and it happens it does not accelerate as was mentioned on the SHO list, it just shuts off.
-No issues with the tach.

Swapped the right front abs sensor and it worked fine for about an hour then back to the same crap. Now the question there is if that is the only sensor used for spped input*? Is it in fact a conglomeration of the inputs? Any way to test the sensors without a swap out?

Any ideas? Could it be the ABS controller without tossing the ABS light? Possible wiring issue? Anyone know where it's routed after the plug?




*- RF referenced here in last listing:
http://www.v8sho.com/SHO/ABSSpeedometeCruise.htm
yet here the LF is referenced with regard to the speedo:
http://www.v8sho.com/SHO/Intermittent Speedo.htm
and here it seems to imply the use of a conglomeration of the inputs:
http://www.v8sho.com/SHO/abssensor.html

 

[Red Devil]

Oh before I forget, the first time I pulled the codes I got a c2000 as well. Never has come up since. Isn't that a traction code or some such? If incidental ignore. Thanks!

 

[me6894]

isnt there a vehicle speed sensor on the transmission also? if so i would check the wiring going to it and test it

 

[SHO#7]

Our VSS runs through the ABS. I have to think about if the ABS module can set a VSS code. I have not see that before in our cars, since we do not have an actual VSS. Possibly the TSS could set this code...?

Mike

 

[SHOZ123]

I would try taking the connector off and making sure it is clean. Otherwise it may be time for a used ABS controller. Which is not fun to change at all.

 

[Red Devil]

I'll be trying the connectors tonight then. What fun. If I have enough light I'll try and test the harness as well. Already started trying to find a new abs box just in case, no luck yet.

 

[Red Devil]

DESCRIPTION
The Vehicle Speed Sensor (VSS) a magnetic pickup that sends a signal to the powertrain control module. The VSS signal tells the powertrain control module the vehicle speed. The PCM uses this signal to control shift scheduling and electronic pressure control.

SYMPTOMS
Harsh engagements, firm shift feel, abnormal shift schedule, unexpected downshifts may occur at closed throttle. Torque converter clutch will not engage.

DTCs
P0500, P0503, P1500, P1501

NOTE: P0500 may also be set by a low transaxle fluid level.

also it has this listed......'


DESCRIPTION
The The anti-lock brake system (ABS) uses two sets of variable reluctance speed sensors (two front and two rear) to determine vehicle speed. Four anti-lock sensor indicators (one each wheel) rotate past each wheel speed sensor. The signal generated is proportional to wheel speed and is sent to the anti-lock brake control module. A vehicle speed signal is then broadcast by the anti-lock brake control module on the Standard Corporate Protocol (SCP) Data Link to the powertrain control module as a vehicle speed input signal.

SYMPTOMS
Harsh engagements, firm shift feel, abnormal shift schedule, unexpected downshifts may occur at closed throttle. Torque converter clutch will not engage. Elevated EPC pressures.

DTCs
P0500, P1500, P0503, U1039

There was a pic there as well of a vss (goodie), but I'm starting to think I'm going to check the wiring, connections and then I'm going to shoot for a new controller. Anyone have a bead on one?

Mike, you think maybe the TSS could be used as part of the speed calculation? It may explain why the ABS light does not come on but I still get similar results of failure. I'll see how much one is and if cheap enough will try that fot s+g. Thanks!

 

[MaxEvo99SHO]

my car started doing the same thing last night- i hit a bump and the speedo died, overdrive on off flashing, my tranny is new i know its not that, where is this ABS control box? im goin to check the VSS on the tranny maybe just swap it out for the **** of it- we will see! someone help me lol- thankx guys

 

[NebraskaSHO]

I don't beleive there is a VSS on the transmission. I've been wrong before...

ABS box, you ask and shall recieve!





It's the SHO only box. Underneath the battery tray which is a total PITA.

 

[naval-avi8or]

There is no VSS on the GEN 3 SHO tranny. You can loose the speed signal from the ABS and not get an ABS light. ABS light will only indicate failures that affect ABS operation and there are failures of the speed signal that have NO affect over its operation. Does your VAPS work or has your no/low speed steering hard this can help determine if the ABS box is putting out the signal at all or if something else between the ABS, Speed O, PCM or SARC box hass issues. The speedo itself has four inputs Batt, + start/run, neg and speed input. While I was modifying my cluster I had issues getting the speedo to work, while troubleshooting it I swapped two wires and I lost my VAPS.


What's interesting is the O/D light flashing as I'm not ssure how the two would be related other than a electrical failure within the tranny thats shorting the speed signal provided to the tranny as well.

 

[SHOZ123]

I had my ABS module fail. At first it just shut itself off with the ABS light on. Then I started having the speedo drop out. When this happened the car would not shift into 1st when at a stop. And the 2-3 shifts were really weird going high in rpms even with light throttle.

 

[MaxEvo99SHO]

aiiight guys i appreciate the help!! im goin to the junkyard right now to get another ABS module- so im assuming that after hookin all this up and everything i will need to bleed the system? the od flashing is bothering me since the tranny is new, but it did it the second the speedo stopped workin, like wtf, lol just after i just put my whole interior back in! the sho will have all black leather interior- just like my GENII that i love all new leather yummy, but this shit has to stop so i can enjoy it!!!

 

[SHOZ123]

When you disconnect the lines from the module bend them up a bit. This will keep any air out of the lines. The 4 output lines will be OK because the module will have the internal valves shut. The two input lines from the MC will drain the MC if left unbent so they are self bleeding.

What I did after the torture of installation was go out on a gravel road and exercise the ABS about 10-15 times. Never cracked a bleeder screw.

 

[bacernate]

i see you live in the ne in the rust belt. i don't know if it's prevelant to the sho or not,but have seen many cars with cracked tone rings on the axle shaft due to the rust. check the fronts and make sure there ok.
thank god i live in colorado now!!! not iowa

 

[Red Devil]

Allright, finally an update. I swapped the controller. It was a used one I got from midnight, I've gotten parts from him before and never had issues so my -assumption- as of right now is that it is a good controller and there is another issue. I haven't had a chance to bleed the brakes and take it for a drive to see if I still will get the odd tranny shifts, but I figured I could see what you guys come up with for ideas I could keep in mind when digging into it next weekend.

 

[SHOZ123]

Does your speedo work? The ABS is dead then you will have no speedo reading.

 

[midnightauto]

if you are not logging a vss it could be a bad wire connection or the mod went bad or was damaged during removal or installation. If it is a bad mod let me know I will take care of it.

 

[Red Devil]

Is there a way to tell if the mod is bad? I doubt it was damaged in shipping or install, that's why I'm assuming that is good and the trouble may be somewhere else.

Is there a way to bench test them? I'm going to bleed the brakes this weekend and go datalog it and see if the PCM is seeing a signal at least. Hasn't thrown a code yet but I only went up the driveway (1/10 mile) and back because of the brakes. I'll let you guys know. Thanks!!

 

[midnightauto]

pin 12 on the mod (gry/black) wire is the vss output. if there is no voltage output it is probably the mod. shoz123 can probably tell you what the output range should be. As I said in the email I drove the car to check the trans and the speedo worked then. That does not mean I did not damage it when removing it. that is always a factor with used parts

 

[Red Devil]

Can't see how it was damaged, though I guess anything is possible. Backprobing that wire for signal ok or is it 'special'?

If only I were getting paid for this job.


Thanks man!!