Tach problem on 99 conversion

4

4x4 Nut

New member
Hello, Just completed a P-pump swap on a 99 & turned out very nice. A few bugs that got worked out, but it's running & my last thing is getting the tach to work. The crank sensor is still installed & plugged in (actually never unplugged this sensor in the process). The volt meter shows that the alternator is charging which my understanding is the ECM uses crank signal for both of these. The only trouble code I have is related to connection between ECM & VP44 (which of course doesn't exist now).

One note that I make just in case. At some point in the past, someone changed a wire coming off the TPS & going to the computer on the passenger side firewall (behind air filter). I removed the added in wire & reconnected it as it should be. I'm not sure if this was because of a wiring issue or some attempted modification.

Any thoughts or suggestions are appreciated. Thanks guys!
 
Drove it some tonight & everything else seems good. With a scan tool connected it shows engine speed on the crank sensor, but nothing on the cam sensor. Everything I've read says tach & alternator take signal from crank & not cam, but is that true? Could it be that the tach is off the cam sensor?
 
Did you use a cam sensor adapter or just not use the cam sensor? I just did a swap on a 99. The tach worked fine, but I installed the cam sensor with an adapter.
 
Yes, the cam sensor is installed using the adapter/ spacer with positioning of the sensor towards the cam center line. My sensor didn't fit correctly & would bottom out against the cam gear before fully seating into the hole. I ended up spacing it with a couple small washers. Did your's fit OK? Thanks.
 
Mine needed a couple of washers to space it out too. But everything worked normally after it was all done. And FYI running a separate signal wire outside the loom for the tps is done in an effort to reduce electrical noise to help reduce torque converter lockup issues. ATS, among others, recommends doing it.
 
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Thanks for the replies guys. And Yotadzl, thanks for the info on the TPS wire. This one's working well now so I'm going to leave it alone. At least for now.
 
Well it's fixed..... By itself. I fired the truck to move it today & the tach is working just fine with nothing done to it. The truck's been setting for right at a year & only thing I can think of is the tach decided to stick & then freed up this morning. Goofy, but I'll take it. Thanks for the replied guys!
 
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