Jeep Q&A: LED Lighting, Grinding Noise, Lift Kits and More

In your Jeep Creep questions, please list your first and last names, your hometown, and your state/province/country, so that we can publish that information here. If you don’t provide this information, we may not be able to publish your question and answer. Don’t forget to be as complete as possible with the description of your Jeep and its problems, too. Send your Jeep questions to editor@off-road.com, Attn: Jeep Creep.

More Jeep Creep Q&As
November 2016 - Ignition Questions, Heater Trouble, Brake Lights Issues

October 2016 - Off-Road Tire Upgrades, Winter Prep and More

September 2016 - Air Horns and Communications Add-Ons

No Jeep recalls from NHTSA this month 

TJ Speedometer Change
I have a 2005 Jeep TJ and I’ve installed 35-inch Yokohama Geolandar M/T tires along with 4.88:1 differential gears. When I compare the Jeep’s speedometer to the speed on my GPS it’s way off. What can I do to correct my Jeep’s speedometer?

Gary Johnson
Phoenix, AZ

Well, Gary, you didn’t tell me whether you have a Rubicon, a Sport, or another trim level. Either way, you’re probably going to have to find a competent speedometer shop in the Phoenix area. If you don’t have a Rubicon, and you’re comfortable with hand tools, all you have to change is the plastic speedometer gear. Quadratrec can help you with the gear and there is a gear chart at here. Rubicons require an electronic modification, which means a Jeep dealership or a speedometer shop.

LED Guru
So I hooked my 50-inch LED bar to a relay and spliced to my fog circuit. It all works well except for the fact that I cheaped out and used wire I had on hand, which I don’t think is thick enough. What is happening is my 20-amp fog light fuse is melting in the under-hood compartment (which is odd because I thought it would blow first). My question is, should I go back and rewire the whole thing? Or do I just need thicker wire from the light to the relay? Or run new wire from the battery to the relay? The reason I ask is because the wire I used is thicker than the factory wire supplying the fogs. So thicker wire from the fogs to the relay seems pointless.

Jesse Williams
Glen Lyon, PA

My guess, Jesse, is the relay is hooked up wrong. Sounds like you are powering the light bar with the fog light power instead of the wire coming from the battery. Go back to your instructions and check to make sure everything is connected properly. The fog light circuit just actuates the relay; it’s not supposed to supply any power. Also, your light bar should be triggered by the high beam circuit, not the fog light circuit. Fog light circuit will only work on low beams; you’ll want the light bar to work with the high beams.

JK Heating Problems
I’m having issues with my JK’s heater working on one side and not the other. What is the problem?
Angela Hull

Your vent motor could be stuck—the blend door is electric on a JK—or it could be a problem with its wiring. Either the blend door actuator has gone out or your heater core needs to be replaced. If it’s the heater core, the whole dash has to come out to replace it. The heater core can get clogged with casting sand from the engine and doesn’t flow through the whole core, causing hot air to blow only on the passenger side. Remove your glove box compartment and to the left side there’s a connector. Push it back in because it gets loose. If it’s the blend air door control, you can Google it and find a YouTube video showing you how to reset it (the air switches have to be turned a certain way).

Grinding Noise
I have a rotational grinding noise. It’s loudest and most noticeable while coasting between 30-50 mph; almost like a brake dragging. Sounds like the noise is coming from the center front/middle of the Jeep. When I push in the clutch while coasting, the noise goes away. When I let it out, it happens again. I cannot replicate the noise while sitting still with transfer case in neutral. The things I've done already:

- Checked brakes
- Checked wheel unit bearings
- Removed front driveshaft
- Replaced clutch, pilot, and throw-out bearing
- Changed and checked all fluids and everything looks normal.

Short of it being something inside the engine, transmission, t-case, I’m not sure what it could be. Also, the noise is gradually getting louder. Noise started couple thousand miles ago.

Mark Debolt

Lift it on a rack and run up the rear wheels while checking for the noise. If you can hear it, you can track it down. If you can’t hear it, then more than likely that means it’s in the rear driveshaft when at normal. If you don’t have access to a rack, buy a pair of jackstands and use them to safely lift both rear wheels off the ground.

TJ Lift
I have a 2005 Wrangler Rubicon. I want to get a lift kit put on it with 33-inch tires. I’m not looking to lift it more than 4 or 4.5 inches. Just a little bit more clearance for rock crawling but not too much since it’s my everyday vehicle as well. I’ve had a ton of advice, like Old Man Emu, short arm as opposed to long arm, do it a little bit at a time, spacers, and so on. What do you recommend for my lift kit?
Brian Babin
Las Vegas, NV

A 4-inch lift is an excellent choice, and you needn’t go any higher, Brian, unless you want to get into more severe rock crawling and want to run 35- or 37-inch tires. My CJ, LJ and JK have all had 4-inch lifts (the CJ and LJ also have a 2-inch body lift). My CJ has a Skyjacker lift, the LJ has a TNT lift kit, and the JK has a Rancho kit, so almost any kit will work for you. I suggest you go online and order catalogs (or look at the products online) from 4-Wheel Parts and Quadratec. Check prices, read the descriptions, etc., and make up your own mind within your budget. If you’re in a bit more of a hurry, drive over to the 4-Wheel Parts store and look at their lift kit displays. Short-arm kits are fine for most of us; long-arm kits are for those who want more extreme trails with extreme articulation.

Fading Fuel
One morning, about two weeks ago I tried starting my Jeep. I unlocked it with my remote, turned the key and the first thing that I saw was that my fuel gauge did not respond and that the empty warning light came on. This was very strange as I had just filled it up the day before. I tried turning the ignition and the engine cranked over but did not start. Can you help me?

Tony Swats
Amarillo, TX

It sounds like someone siphoned out your fuel, Tony. Or perhaps a low spot in your fuel line sprang a leak and everything drained out? Check for stains around the Jeep. If you think you still have fuel, try a squirt of starter fluid; or maybe a gallon of new fuel?

Fouled Four Banger
I have purchased an ‘89 Wrangler with the 2.5L engine. Someone changed it to a 2-bbl carb with an adapter to the intake manifold. I purchased a Rochester Monojet and an ‘84 intake manifold and the Jeep runs fine, but under load it retards, or something, and runs like crap. The distributor wires are not connected (there are three of them). I also purchased an ‘84 distributor but it looks the same as what I got. The wiring has been all chopped up. I have the isolator block and coil and tried the direct approach with the same result. Is this possibly a weak or intermittent spark? Timing is bouncing around. Is the computer somehow still connected to the motor? Does the module in the distributor now need power or a controller?

Tom Durrel
Kansas City, KS

You have to find an early distributor and module to run the ignition or fix the OEM injection system. Why would anyone replace EFI with a carburetor? Also, buy yourself a good shop manual with a thorough troubleshooting section.

Gobbed-up Gauges
I have a 2000 Wrangler 4.0L. Recently my gauges started acting funky; voltmeter would peg over 19 volts then all the gauges would quit, also the radio would quit, then it would come back on and the voltmeter would peg again. I hooked it up to a computer and got a P0622 “Generator field not switching properly” error code. I have replaced the alternator and ignition switch, but it’s still the same. Also, even when my voltmeter says 19 volts, the actual output from the alternator is correct (15.5V). Could the PCU be bad?
Joe Zavalla
Lansing, MI

You need to verify all your ground contacts, starting with the ganged dashboard ground. Also make sure the engine-to-frame ground strap is connected with clean contacts. You may need to buy a Jeep maintenance manual with wiring diagrams to ascertain all your ground contacts. If the grounds check out OK, verify that your control unit is operating properly. Correct voltage should be 14.5 at the battery when charging system is working properly.

Synthetic Oil
I was told not to run synthetic oil in flat tappet engines. I should run Rotella or Joe Gibbs oil. My 4.7L stroker runs good but a little hot. And my Crane cam didn’t last 8,000 miles. Comp cam is okay so far. Biggest help was to remove restricted head pipe (I made a true 2.25-inch pipe); factory opening was 1.75-inch inside. And the engine runs cooler.

Dan Kiefer
Cleveland, OH

Synthetic oil is okay if the cam is broken in correctly with the right additives; just follow the manufacturer’s suggestions. Running hot could be anything; you’ll have to track that down to be more specific.

Sputtering Engine
I have a 1988 YJ six-cylinder. The problem I’m having is that it will idle well, but going down highway it will lose power and start to go dead. Sometimes putting foot on brake and revving engine will keep it going but must be kept at high rpm. Quit on me this past weekend, towed home, wrecker left I got in tried to start Jeep, fired right up. Not the first time this has happened, last time replaced carb and it has been running good for almost 2 years. Any ideas?
Phil Durrett
Red Bay, Alabama

The problem is somewhere in your fuel system. Either the tank isn’t venting properly or the pickup tube is clogged. You could also have problems with the fuel pump—becoming heated or clogged—or the filter. Start at the engine and trace the fuel line backward, checking fuel delivery at each connection. BE CAREFUL and have a container ready to collect the expended fuel. You don’t want a fire!

In your Jeep Creep questions, please list your first and last names, your hometown, and your state/province/country, so that we can publish that information here. If you don’t provide this information, we may not be able to publish your question and answer. Don’t forget to be as complete as possible with the description of your Jeep and its problems, too. For some reason the questions have fallen off, and I know we haven’t answered all your Jeep technical questions. There are no dumb questions; only unasked questions. Send them in and try to stump us.—Jim Brightly

More Jeep Creep Q&As
November 2016 - Ignition Questions, Heater Trouble, Brake Lights Issues

October 2016 - Off-Road Tire Upgrades, Winter Prep and More

September 2016 - Air Horns and Communications Add-Ons

As usual, each month, I’m shouting out a huge THANK YOU to Paul Schupp at Rock Lizard 4x4 in Kingman, Arizona, for his invaluable assistance in answering many of the Jeep Creep questions.