Zap Racing

On my 89 IROC--350/700R4--cruise control--speedo quit working. code 24

Is this car an electronic driven speedo rather than a cable driven? What would be the most likely thing wrong and/or what would be the correct trouble shooting procedure to locate what needs replaced?

Thanks!!!
Craig

five7kid

iTrader: (14)

Speed sensor & circuit, I'd say.

DENN_SHAH

iTrader: (1)

hey Zap, 1 part of my book shows it uses a cable, another part shows it has an electronic speedo. im pretty sure it is electronic.
sense its setting code 24 the ECM isn't getting a signal. the signal comes from the speed sensor to the speed buffer & from there it goes to the ECM & cruise control.
the first thing to check would be the fuses, but because you said nothing about the other gages not working i doubt there is a problem with them.

the following are the most likely things to be wrong,
the next thing to check is the wiring at the speed sensor at the tranny as the insulation may be breaking down & shorting out. the next thing on the list is the speed sensor itself. if you have a
known good sensor with a gear on it you can plug it in & have your wife watch the speedometer while you spin the gear on the sensor with the key on & the engine off, if the speedo works like
this either the old sensor is bad or gears inside the tranny are worn out.

if everything checks good to this point, the wiring from the speed sensor to the buffer will need to be checked for shorts to each other, to ground & for an open circuit. if everything is still looking
good, check the power & ground at the speed buffer.
normally the wiring doesn't have problems other than the last foot or so down near the sensor. also the speed buffers don't go out very often.

Trickster

Hey DENN_SHAH,

His is the same as mine and it is cable driven. He should have the rpo codes "E5Z", "E7Z", & "E9Z".

DENN_SHAH

iTrader: (1)

cool Trickster, i couldn't remember what year they changed over. i was thinking in 89 the TBI cars had a cable but the TPI cars were electronic.

with my books, i believe what i see, i don't know how many times they have wires shown in the wrong position in a connector & other things that i know are not right.
the best 2 so far was on a ford i was looking up a trouble code for, i forget the code number, but first thing it said was "there are no other possible causes" or the location of the knock sensor on a mopar "under dash, left side of column"

Zap Racing

THANKS for the info.

Craig