92Yoda

ok so today on my way home from work my speedo ctout and my chk engine light came on at the same time, i got home and turned my truck off then on again, and the light was off but the speedo still doesnt work. I checked my diagnosis terminal and found that my o/d light was flashing 4 times pause then 2 times, and my check engine light was flashing 2 times pause then 4 times, 1 time pause then 2 times and flashed 4 times paused and then 2 times. I love that i can diagnose my truck with a paper clip but i never know what the light patterns mean, so now I'm here, just a heads up the first two engine codes i said were already flashing before today theyve been like that for awhile, but I am unsure of the 4 flashes pause then 2 times and also I am unsure of the o/d light flashing 4 times pause and then 2 times... does anybody have any answers? greatly appreciated in advance

Cyberman

If the speedo stopped working, that's why the light came on.

The computer uses the speed sensor for an input.

Check your speedo cable.

yotie

ok so your flashing a "42" "24" and a "12"
code "42" = vehicle speed sensor signal.......................diagnosis--no "IDL" signal or no "nsw" signal or "A/C" signal to "ECU" with the terminals E1 and T shorted....NO "STA" signal to "ECU" for 8 seconds when engine speed in between 1,500 RPMs and 4,000 rpm and coolent temp is above 80 degrees except when racing the engine.....
"trouble area" --vehicle speed sensor circuit
vehicle speed sensor
ECU

code "24" = intake air temp. sensor signal... Diagnosis----open or short circuit in air intake temp.sensor signal (THA)
"Trouble area" .....intake air temp sensor circuit
intake air temp sensor
ECU

code "12" = rpm signal..---- DIAGNOSIS......NO "Ne and G" signal to ECU within 2 seconds after the engine is cranked
"Trouble area"..... Distributor circuit
Distributor
Starter signal circuit
ECU


I'm just letting you know what the book is telling me on what your codes are reading,,,as for why exactly they are throwing those codes,,i don't have an answer.....

i had my check engine light come on with 2 different codes due to a spark plug wire came loose,,it was giving me air fuel ratio code and EGR code,,,,found the problem with the spark cable wires and fixed it and disconnected both red and black battery cables to reset because just the positive was not clearing the code.....

92Yoda

could you explain to me why i would get a code 12 if my tach is working properly? also somebody told me a code 24 could be the Air flow vane, so i replaced that and the vehicle ran abit better but the code was still flashing so is it for sure the air temp signal? and does the o/d light flashing have any significance?

yotie

check my post again,,,,,i updated it

92Yoda

haha ok thanks, I can kinda make out what that means, silly vehicle language

scope103

42 on the OD light is also caused by loss of VSS1 http://personal.utulsa.edu/~nathan-b...31diagnosi.pdf (you have two speed sensors; VSS2 is before the transfer case and controls the main functions of the transmission, VSS1 is after the transfer case and runs the speedometer and other things). I believe that you have the electronic VSS1 (no cable to the speedometer) but it is easy to check. If there is a cable coming from the back of the transfer case, you don't have electronic VSS1.

The electronic VSS1's do fail around this point in your vehicle's life. RockAuto carries them for around $250. There is a testing procedure but it is rather involved.

Of course, you do need to fix your intake air temp sensor and find the source of your missing NE signal (probably an iffy distributor, but there are plenty of causes).

The manual is your friend.