'98.5 truck/ '92 engine/ Tach problem

[MEby]

How do I get the tach in the dash of my 1998. 5 truck work with the 1992 12 valve engine that was transplanted in my truck ? I would appreciate an help.

 

[dpuckett]

Set the gap on the tach sensor to . 050" +/- . 001" If that fails, you may need to run a new(er) tach pickup off the harmonic balancer. If they are not compatible, it wont work. Did the 98 come with a diesel, or is this a gasser conversion?



Daniel

 

[MEby]

it came with a 24 valve. 1st owner replaced 3 injection pumps due to lift pump failure, all on less than 60,000 miles ( OUCH ) before he got sick of it and swapped the engine. also due to a lot of crappy employees. I guess he didnt know about FASS.

 

[MEby]

How do I get the tach in the dash of my 1998. 5 truck work with the 1992 12 valve engine that was transplanted in my truck ? I would appreciate an help.

also would it be possible for someone to give me detailed instructions on how to go about this?

 

[cerberusiam]

Tach should be driven off the CPS (crank position sensor) and should not matter what year the engine. I think the CPS on the early 24V's was in the bell housing above the starter. I would need to dig up the FSM for that year to make sure. As long as the original pieces were used the tach should work fine if it is hooked up and sensor is good.

 

[MEby]

I've been studying the shop manual for '98 and near as I can tell it says the tach is run by the pcm which receives its signal from the throttle position sensor (TPS) ? am i right? my next question is does my '92 12 valve ctd have a TPS ? can I mount one on my pump? am I all wet ?

 

[cerberusiam]

I've been studying the shop manual for '98 and near as I can tell it says the tach is run by the pcm which receives its signal from the throttle position sensor (TPS) ? am i right? my next question is does my '92 12 valve ctd have a TPS ? can I mount one on my pump? am I all wet ?

Your mixing two different systems here so there are differences. The VP engines had 2 computers on them. The one mounted on the engine block was the pump control unit, the one on the firewall is the power train ccontrol unit.



Your truck has an APPS which is about the same as a TPS but runs much different voltages and more functionality. The tach signal will come from the CPS and probably be processed thru the ECU then passed off to the PCM. The TPS will not provide a tach signal.



If you are not getting a tach signal it is likely some wiring is not hooked up correctly.

 

[MEby]

Your mixing two different systems here so there are differences. The VP engines had 2 computers on them. The one mounted on the engine block was the pump control unit, the one on the firewall is the power train ccontrol unit.



Your truck has an APPS which is about the same as a TPS but runs much different voltages and more functionality. The tach signal will come from the CPS and probably be processed thru the ECU then passed off to the PCM. The TPS will not provide a tach signal.



If you are not getting a tach signal it is likely some wiring is not hooked up correctly.

Thanks for the info, I'll have to try that. What does APPS stand for ? When they put in the 12 valve they didnt even try to hook up half the gauges like the tach, oil pressure, water temp. :{ they just added an oil pressure and water temp gauge under my dash. I'm trying to make the origanal gauges work. After I get the gauges to work than I'll start on things like connecting the cruise control and so on. Fortunately they left the wiring harnes intact.

 

[dpuckett]

APPS- Accelerator Pedal Position Sensor.



The gauges should work with OEM sensors from the 92; may have to get em off a 98. May have to rob some off a parts engine or get new ones from somewhere. A FSM with wiring diagrams would be a big help.



DP

 

[MEby]

thanks for all the help guys. -matt