Snowplow Forums banner

1 - 12 of 12 Posts

·
Registered
Joined
·
85 Posts
Discussion Starter #1
I picked up a 1998 z71 yesterday and I have a couple challenges I'd like to address as soon as possible. I used to be a motorcycle mechanic so I have a general grasp of mechanical things but I don't have one ounce of acquired knowledge when it comes to trouble shooting these trucks. You guys have always been great! Thanks in advance for the help.

Problem 1: Truck will not come out of park after it is started or even with ignition turned all the way to On. The only way to get it out of Park is to turn they key softly forward and as soon as the shifter location indicator lights up orange on the dash, you can take it out of park and start it in Neutral, then do your driving etc. However if you ever put it back in Park, even with the motor running, it won't come back out. And yes, I've mashed the brake pedal to the floor, lol.

Problem 2: Cruise control doesn't work and I don't have a trouble shooting / diagnostic chart.

Problem 3: The volt meter reads low but the battery doesn't go dead etc. With headlights and AC on it reads around 11.5v, shut them off and it goes up to around 14v. I drove it home 2.5 hrs with headlights on and AC running. Strange part is the Starter doesn't drag, headlights aren't dim, everything seems fine except the gauge and the amount of fluctuation I see.

Challenge 4: I was told by the previous owner that from the factory the truck had 3/23 gears and he changed them to 3/73 to make it better for pulling a trailer in 3rd gear (out of over drive). He did change both front and rear ends so they match. Can you give me some pros / cons about leaving it this way? I do not plan to plow with this truck. I plan to use it for hunting trips and running feeders here at the ranch. Rims are factory and tires are 285/75-16
 

·
LetsTalkSnow.com - Moderator
Joined
·
4,902 Posts
When you speak of the volt meter, are you referring to the dash unit? If so, get yourself a digital volt meter and check the battery with the same load on it and see if they match. If the handheld meter reads higher, the problem could be a dirty contact somewhere of a faulty meter.

The rear end ratio will cost you more in fuel. The lower gears take some stress off the transmission but make the engine spin faster to maintain the same speed. If you aren't planning to do towing, plowing or hauling heavy loads you could consider reverting to the former ratio, but I'm not sure it would be worth the expense. If you have the old ring & pinion sets to put back in, perhaps so but you'll need someone with the tools and skills to set them up properly for you. If they aren't shimmed correctly you can tear up the gears.
 

·
Registered
Joined
·
85 Posts
Discussion Starter #3
Yes, the volt meter gauge in the dash. I'll get a hand held and check it. Hope it's that simple!:)

Actually yes I do have the original clusters for the rear and front ends. So do I have lower or higher installed? It seemed like they would be higher because at 70mph my tach is only showing 1,800rpm. It never even touched 2,000 at 75mph. Now that was in over drive. If I pull it into D at that same speed it's almost 3,000 rpm. I just don't really understand what the ratios #'s mean. The guy who owned it was a tech at a Cadillac dealership and he said it was changed so you could haul in D, not using OD and still be where it could get good fuel mileage etc.

Thanks!
 

·
LetsTalkSnow.com - Moderator
Joined
·
4,902 Posts
This is a bit confusing, but the lower the ratio number, the higher the gear. So you have a lower gear than was originally equipped. What the ratio number means is the driveshaft must turn 3.23 times to turn the wheel once, or 3.73 times with the lower gear. A 4.10 is lower yet, so the engine has to spin faster to maintain the same highway speed.
 

·
Registered
Joined
·
85 Posts
Discussion Starter #5
Ah. That completely makes sense. Could I have my information backwards then? Like that truck has 3.73 factory and they installed 3.23? That would explain why the tach is so low at 70mph. Anyway.......

Any ideas on why it won't come out of park?
 

·
Registered
Joined
·
1,080 Posts
Jumping in here. Two things:
1. there is usually some sort of solenoid powered from the brake switch that releases the shifter. Yes, you mashed down on the brakes, but did your brake lights come on? Could be a fuse, wire, solenoid.
2. If the previous owner changed the axle gears, but did not change the spedo gears, your spedo is off. Meaning that going from 3.23 to 3.73 gears, when your speed reads 75, your only actually going 65. I suppose that's a good way to avoid speeding tickets.
 

·
Registered
Joined
·
85 Posts
Discussion Starter #7
I do have brake lights and I checked the speedo with a gps, at 70mph on speedo you are actually doing 68mph so it is really close. I'm guessing he changed whatever that part was you mentioned. I do know the truck has a programmer and I'm guessing he could have changed the calculations there if it isn't cable driven.
 

·
Registered
Joined
·
748 Posts
Never heard of a 98 Z71 equipped with 3.23. Most were 3.73, some 3.42. If you have the old gears they should have the ring/pinion tooth count stamped on the edge. 41-11 for 3.73s for example. Or you can count the teeth.....

Where is the speedo gear on a 98?
 

·
Registered
Joined
·
85 Posts
Discussion Starter #9
I'll have to did them out but I think that's what they did was take out the 3.73's and changed to 3.23's. That would explain a lot. Now that being said, should I leave them? Will it help my mileage?
 

·
Tileman's Boys
Joined
·
1,094 Posts
That truck should have left the factory with a 3.73 gear as it was the highest gear offered in a Z71. with the 285 which are taller than factory it shortens the gear even more so in essence you have about a 3.08 ratio now. As for it not coming out of park im betting there is something wrong in the column with the key and tumbler or the gear. so its binding in the column.
 

·
LetsTalkSnow.com - Travel & Bar Consultant
Joined
·
2,029 Posts
Don't those years have a BTSI (brake to shift interlock)?
If so thats the shifting out of park problem.

(Can't remember if my 07 had it..................)
 
1 - 12 of 12 Posts
Top