ASR Limp Home mode

[aldedmon]

93 500E 160Kmi:

If I only drive the car in the neighborhood, it performs flawlessly . Down shifts appropriately, and everything is grand. As I approach fwy speeds, car still works fine , up to 70 mph.... as I slowly accelerate to that magic number...the ASR light comes on and I go into limp home mode 8 / 10 times. If it doesn't go into limp home /ASR mode, everything works fine except it doesn't do a down shift after that 2nd set of dots on the speedo(. At 40, : at 70), if I press hard and engage the button under the pedal it down shifts and hauls ass. But as lower speeds I can make a "pressure " down shift by regulating the pedal pressure at and speed 30-69, right before the :.

I replaced the MAF and TBA and all the computers 22 months ago. Mechanic miss connected some stuff and fried the computers is what the mechanic Mike at TGA here in Houston replaced and it was fine tine I had the tranny B2 piston seal replaced and the throttle cable replaced. I got it back and it's been acting up ever since.

Also placed 285/35/18 Mich on the back. 255/35/18 on the front .I did also notice that the blue OVP fuse over near the master cylinder was literally fried one day as I tried to trouble shoot it. I replaced it and it hasn't blown again .... that's all the data I have . Car starts right up. Shifts good. Drives well, but this ASR Limo home mode is driving me crazy

 

[sheward]

Others here with more knowledge may see a connection between your transmission work and the ASR problem. I suspect the tire sizes you choose could be the cause. 285/35/18 = 25.85 diameter. 255/35/18 = 25.0 diameter. Stock tire diameter is 25.75. An issue with the tire diameters would tend to manifest at speed as you are seeing.

245/40/18 at 25.7 diameter would be a better choice for the fronts, or 255/40/18 at 26.0, should this turn out to be the only issue.
drew

 

[FU2]

There is no OVP (like on the OVP relay on other merc"s)fuse on a 500e..the fuse you are talking about are for something else.
The tire size beeing different between the rear and front is most likely the culprit.different tire size does not mean automatically trouble..but when you have the same profile,on different width tires.....that is what potentionally screws up stuff...the circumference on these two different size tires are off ..
If you do have a set of same diameter tires...do try them on.

 

[aldedmon]

Ok , I'll throw the set of 275/35/18 that I have lying around on it and see what happens.
No OVP... can someone tell me what that blue fuse under the clear cover near the master cylinder is for?... I've also run larger 265 /35/18 in the front with other rear combinations. I guess I've just always been lucky

 

[gsxr]

Can you confirm the tire sizes you are running? 255/40 front would be correct with 285/35 rear; or 245/40 front with 275/35 rear. Front & rear diameter / circumference should be within 1-2% max to avoid problems, things start to get screwy around 4% or more. If the rear tires are smaller diameter, ASR will go nuts. If rears are larger, cruise control won't work over a certain speed.

But anyway: Codes! What codes are present? Any time you get limp mode, codes should be stored, and probably on multiple modules. Clear 'em all out, go make it limp on the highway again, and check to see which codes triggered. That should help pinpoint the issue (assuming it's not just tire size).

Very odd this all started after you had the tranny control engine throttle cable replaced.

The blue ATC (GM-style) fuse under the clear cover MIGHT be for the dealer-installed cell phone, but I'm not positive. I always forget what that one is for, it's some oddball auxiliary item...

 

[aldedmon]

255/40/18 Fr , 285/35/18 Rr.
I've Not the had the tranny control cable replaced.
I had the Throttle Cable replaced and the B2 Piston and other passenger side tranny seals replaced

 

[gsxr]

255/40/18 Fr , 285/35/18 Rr.

Those sizes are perfect, should not be an issue there.

I've Not the had the tranny control cable replaced. I had the Throttle Cable replaced and the B2 Piston and other passenger side tranny seals replaced

AH! Thanks for clarifying. My guess is the throttle cable was not adjusted correctly, since the problem started right after this work was done. If the throttle cable is not adjusted EXACTLY right, you'll get limp mode. However, it may still be something completely different that is a coincidence. Again - need the error codes to pinpoint the cause.

 

[FU2]

Those sizes are perfect, should not be an issue there.

Of course..that changes it all..cause that is not the tire size that was mentioned in the first post

 

[aldedmon]

Im so sorry, The Tires are 255/35/18. Im on my way to put 245 40 18 on right now and will report back my findings

 

[FU2]

Im so sorry, The Tires are 255/35/18. Im on my way to put 245 40 18 on right now and will report back my findings

So..once and for all...what tire size do you run at the moment(When the ASR comes on)..front and rear?

 

[aldedmon]

255/35/18 FR
283/35/18 RR

 

[FU2]

okei...then ...the tire size is way off..and it might be the problem right there.
You should then try a set with the same size tire,/ same or within 1-2 percent circumference between the front and rear tires.
OR like mentioned above also....it might be that the throttle cable has not been adjusted properly..this would also play havoc with the asr..but i have a feeling its your tires messing things up