95 S-10 blazer about 143k on it, engine has around 85k give or take a bit...

So as i was driving to school this morning the speedo started to go all wonky... It would bounce from 40 to 60 and go progressively higher if i accelerated... I also noticed as this started the brakes became REALLY soft.. I had to depress nearly all the way for them to engage.

So when i parked it i turned it off then abck on and at idle it was saying around 20 mph...


Any thoughts or suggestions ?

 

What did your voltmeter say when all this was happening? Sounds like an electrical problem to me.

 

To be honest, i was in a rush, and didn't take note of everything: However, i got back in in the afternoon and it did it for about 1500 feet then stopped... I attributed this to the fact it was very cold that morning and something might have been stuck or sticky.. I haven't driven it in the cold since to test the theory... i'll post an update if it does it again... as of now it has stopped and runs perfectly once more.....

Thank you for your reply and i'll be sure to note that if it repeats

 

Ahoy...

So for the last day or so the speedometer has been bouncing around as i previously said.... The ABS and Brake lights come on at ignition, go out as if they passed their self test. engine starts and then after about 6-15 seconds they will come back on and come on and off intermittently. While driving there is a huge power loss, as in cant go faster than about 10 mph... when you give it gas when it is doing this the service engine soon light pops on for a split second then goes out...
Volt meter reads 14 the entire time... oil pressure is good and temp is good.

I have checked the connections at the wheel for the ABS sensors and they seem tight, doesn't look like there is any sort of cut in the wire or any such thing.

Someone suggested alternator... bad ground wire or something... I am taking it to the shop today so I'll keep you updated on that...

Any suggestions would be a great help THANKS!

 

Sounds like a dirty or faulty VSS (vehicle speed sensor) at the back of the transmission (2wd) or transfer case (4wd). This can cause a number of problems including your ABS & Brake warning lights coming on.

I would try removing it and giving it a good cleaning first. If that does not work, then replace it.

 

i had an 88 s10 which had the same problem... and mine only happened when it was really cold outside... it did it until i cut the truck off... but i didnt investigate anymore then that