Engine/Transmission (1998.5 - 2002) P1693, Tach @ 0 rpm, and Limp mode..

[Newf Limo]

Woww, haven't been here since July "05"! I took a couple years off. I remember back when there where only 700 of us... . :-laf



anyway. .



My 01 HO 6spd, hardly bombed (do we still say that here?) 4 Inch exhaust and K&N filter... no chips and stuff, has started to give me an issue now at 160,000miles.



Intermittant, check engine lite, but driveability is normal. Within a few miles, the Tach drops to 0 rpm and the engine derates (limp mode). A minute or so later, engine and tach return to normal. I check the code (via the 3 turns of the key method) and get a lonely P-1693.



After a few short trips, the code Chk engine lite will be out and no further incidence that trip (short trip <10miles). The next time I start the truck, the lite will be on, the tach at some point will read zero while driving, the engine will derate and a couple minutes later I will have full power again.



Note** by derating, i am not talking the APPS "dead Pedal" situation, just has reduced power and may not maintain 50mph on a 4% grade.



Any one run into this and successfully fixed it?

 

[johncameron]

It could be a cam position sensor?

When the tach drops to zero does it still have idle torque?

 

[Newf Limo]

When it drops to zero, I can still drive, just with reduced power. If I didn't climb a hill I would miss the event all together.

 

[johncameron]

If it ever dropps to zero when stopped, release the clutch from a stop in 2nd. If it instantly stalls it's your cam sensor.

 

[Newf Limo]

"Old Timers" disease must be setting in. I found an old thread about a P-1693 DTC that set in a truck, very similar to mine. Turns out, the guys lift pump wasn't working. He replaced the pump for too much money and the code went away. He wasn't having the derating and tach problem though, or maybe I didn't notice it. Yeah, that's right, ugh, that was my post!



I went out and checked, and sure enough, I didn't hear the lift pump kick on at 'start up', and bumped the starter and still didn't hear it. So, I guess I will start this fix with two Ginko Biloba and a new lift pump. :-laf :-laf :-laf sigh... . what a Bozo.

 

[johncameron]

"Old Timers" disease must be setting in. I found an old thread about a P-1693 DTC that set in a truck, very similar to mine. Turns out, the guys lift pump wasn't working. He replaced the pump for too much money and the code went away. He wasn't having the derating and tach problem though, or maybe I didn't notice it. Yeah, that's right, ugh, that was my post!



I went out and checked, and sure enough, I didn't hear the lift pump kick on at 'start up', and bumped the starter and still didn't hear it. So, I guess I will start this fix with two Ginko Biloba and a new lift pump. :-laf :-laf :-laf sigh... . what a Bozo.

I really doubt your tack is related to your lift pump. That may be another problem in itself... ...

 

[Newf Limo]

Well then, won't that be fun. I gues I will start with the pump and then look at the Cam sensor. There is never enough things to do around here. Thanks for the input.

 

[Newf Limo]

OK you win. The Lift pump is in and working, but I still ended up getting a check engine light while driving. Shortly after that, the engine went in to limp mode and the tach read zero again. I didn't loose any speed, just a little power. A minute later the tach kicked in again and the power came back.



How does one check if these sensors (Cam and Crank position sensors) are working or not? The code I get on the dash board is P-1693, will a scan tool read codes that don't show up in the dash, when switching key on 3 times?



The dealer wanted a 1/2 hours labor to read and clear the codes. I know that it only took me and a tech five minutes to hook up the DRB3, set up the 3 cylinder idle program in the ECM and then get back out again. That was at a different dealer, and different state. When I balked at the 1/2 hour, he said, "It takes a half hour for him just to get it hooked up. " I just shook my head and asked how long it takes him to plug in a lamp? I just left after that. I think I will look into buying a code reader. I can't stand getting jerked around by dealers.

 

[analog]

I had the exact same problem. I just got a new cam position sensor ($60) and put it in. . problem went away. Warning: It is not easy to get to that bad boy. It's tucked in behind the vacuum pump.

I can't remember the exact code I got, but it was clear the code meant the sensor was bad. I think the code I had on the dash said there was a code in some other bus, and I had to use a scanner to get that actual code. Many auto parts stores will scan your codes for you for free.

 

[johncameron]

I think it's code 335, 336, 337.

I had one of them when my tach stopped working. A new sensor fixed the problem.

And yes it is a miserable bugger to change.....

 

[Newf Limo]

Wow, my anticipation is just building It's similar to that feeling I get when I realize it is time to trim the hooves on my draft horses. I know when I get done I will appreciate how nice they came out but I will be flat out in pain laying on the front porch hoping someone will bring me a cold beer and some ibuprofen.



I will get it scanned in town this week and figure out if it is the cam, crank, or map sensor and take care of it. I will let you know what I find. Thanks for the help guys. It is good to be back.