Hi there my check engine light is coming on and off periodically on my 91 3.0 5 speed so I pulled the codes but im not sure how to read it. I checked the offroad link which confused me a bit. When I jump the terminals, get in the truck and turn the key to on it takes about 4.5 seconds for the check light to come on, it flashes4 times, then pauses for about 2 seconds, then flashes 2 times, then pauses for about 4 seconds and repeats 4 flashes, 2 second pause, then 2 flashes. Is this a code 4 and 2 or 42? Thanks

 

There is no 4 or 2, whereas 42 (from Chiltons) is SPD signal is not input to the ECM for at least 8 seconds under high load conditions between 2750 and 4000 rpm.

 

Are you meaning if it was a code 4 and a code 2 it would show the 2 first then the 4. The printout of codes I saw had a code 2 and a code 4 as well, or am I reading it wrong?

 

My Chilton's does not have a 2 and/or a 4.. but it could be wrong. What are the 2 and 4 codes that you show in your list, ie: what does your list show them as meaning?

 

That's 42.

if it was "2" & "4", it would be:

• blink, blink
• long pause
• blink, blink, blink, blink
• long pause
• repeat

The general pattern is define by short pauses between digits, long pauses between codes.

 

Thanks that helps.

 

On a 91 3.0 with a 5 speed where would the vss be? I understand with autos the concept of the vss but with a 5 speed what is its funtion? is it possible to cause a bit of surging and somewhat sluggish behavior? thanks

 

we don't have a VSS. As to why your getting that code hell if I know!?

 

anyone ever have a symtom like this?

 

according to the fsm, there is no code 2 or 4, the first code is 12. not for sure, but i think 5sp still use vss for cruise control. try using your cruise control and see if there are any problems with it.(will not maintain speed, doesnt decel or accel when cancel or resume is pressed, sluggish on resume acceleration, ect) there is a way to run diagnostics on cruise, it has its own codes. if you do have problems with cruise, ill post up the page on how to troubleshoot it. i think vss is on drivers side of tranny. brad

 

ok, did a little more checking, and its on the drivers side on autos, for 5sp, vss is basically a ecm input from the combination meter(gauges) it gets it signal from a mechanical input from the tailshaft housing. so it would seem for 5sp, vss is just an electrical input from your gauges, where connector c terminal 10 is ground, connector d terminal 1 is vss signal. i may not be correct on this, the fsm makes no distinction between autos and 5sp in this regard.

 

I have no cruise control. I will check the back of the tranny for the plug, maybe its dirty or something. My speedo has been jumping a bit so maybe thats causing it.

 

hmm, since the speedo is mechanically driven and the vss input into the ecm is taken from the speedo gauge itself, maybe the bounce and the code are realated.