WaltH
Senior Member
On my way home from the Chicago Spyder event in June, I experienced some very strange behavior on the part of my Spyder. Three times the computer spewed out a cascade of fault codes including “check DPS” which culminated with the Spyder going into Limp Mode. I thought I must be getting the much dreaded steering disease, except that the steering was operating just fine. In fact, everything was working just fine, if you didn’t count “Limp Mode”. I was able to cancel Limp Mode by rebooting several times, but the “check DPS” code remained on for most of the next two days.
The day after I got home I took the Spyder to a new dealer about 45 miles up the road. By then the “check DPS” code was gone and there wasn’t much of anything to read in the history file other than some references to speed sensor differentials. The Spyder technician came up with a theory to explain my strange experience that I thought was crazy at the time. Thousands of miles later, his theory makes more sense and seems to be validated by the fact that there have been no fault codes, or any other strange behavior, since then.
The technician said that since I was using automobile tires on the front which were just slightly larger in circumference than the stock tires, I could generate junior level fault codes for speed senor differentials, depending upon road conditions. The front tires would be turning a little slower than the rear which, although an automotive tire, was closer to the stock circumference. Under normal circumstances, the speed differential would be within the tolerance provided for by the system. If the rear tire were to slip a little, such as in a heavy rain storm, the differential would increase and the fault code would be generated.
My experience was the result of a combination of factors. I rode through two days of very heavy rain. The memory cache for the fault codes is very small. When the cache is full, a condition is created which causes a cascade of fault codes to appear which have no relation to reality. The only real fault code was the speed sensor differential which doesn’t appear on the instrument cluster. When the “check DPS” code cascades it triggers Limp Mode which is real. I was in Limp Mode because the computer had a brain fart.
I have been in heavy rain before, and since, with automobile tires on the front and rear with no trouble because of it. On this particular trip I must have exceeded the Spyder’s tolerance for my heresy. It is my understanding that the speed sensors on Ford trucks, and no doubt many others, are adjustable to accommodate a change in tire size. The physical sensor does not change, just the way the computer recognizes it.
The day after I got home I took the Spyder to a new dealer about 45 miles up the road. By then the “check DPS” code was gone and there wasn’t much of anything to read in the history file other than some references to speed sensor differentials. The Spyder technician came up with a theory to explain my strange experience that I thought was crazy at the time. Thousands of miles later, his theory makes more sense and seems to be validated by the fact that there have been no fault codes, or any other strange behavior, since then.
The technician said that since I was using automobile tires on the front which were just slightly larger in circumference than the stock tires, I could generate junior level fault codes for speed senor differentials, depending upon road conditions. The front tires would be turning a little slower than the rear which, although an automotive tire, was closer to the stock circumference. Under normal circumstances, the speed differential would be within the tolerance provided for by the system. If the rear tire were to slip a little, such as in a heavy rain storm, the differential would increase and the fault code would be generated.
My experience was the result of a combination of factors. I rode through two days of very heavy rain. The memory cache for the fault codes is very small. When the cache is full, a condition is created which causes a cascade of fault codes to appear which have no relation to reality. The only real fault code was the speed sensor differential which doesn’t appear on the instrument cluster. When the “check DPS” code cascades it triggers Limp Mode which is real. I was in Limp Mode because the computer had a brain fart.
I have been in heavy rain before, and since, with automobile tires on the front and rear with no trouble because of it. On this particular trip I must have exceeded the Spyder’s tolerance for my heresy. It is my understanding that the speed sensors on Ford trucks, and no doubt many others, are adjustable to accommodate a change in tire size. The physical sensor does not change, just the way the computer recognizes it.
