Forum Discussion

Bucky1320's avatar
Bucky1320
Explorer
Sep 12, 2014

CAT experts?

Thought I would start a new thread about my CAT in my 99' Harney. 3126 and probably a B although CAT doesn't really mention that.

The only thing I have had for a symptoms is that the cruise only works now and then. And mostly not at all. It also seems like when accelerating, you don't get much acceleration at the top of each gear and plenty after the shift. May be the nature of the beast, but I am new to pushers.

Last night I read the codes. I have never seen any check engine lights since I have owned it for a few months. I read 21, 34, 49 and 71. This is where I need help and direction. I don't have enough diagnostic skills with these to know what to do now.

The p/o didn't drive the m/h hardly at all for the last two years. They took it in March and had batteries, filters and oil change done. I have added half a tank of fuel (biodiesel is all I can get in town). I am a little suspect of the work at the dealer though. The receipts say that filters were changed in the generator, but when I tried the geni, it wouldn't run because the air filter was completely clogged with dust. Hmmmmm.

No emergency here, but I think I need to address this issue(s). Help?
Class A
  • wolfe10's avatar
    wolfe10
    Explorer
    Sep 12, 2014
    Bucky1320 wrote:
    Agreed. Is Brett "Wolfe10"?


    Yup. Brett Wolfe= Wolfe10 (Wolfe10 happened to be my e-mail address way back when RV.net got started).
  • lanerd's avatar
    lanerd
    Explorer II
    Sep 12, 2014
    Listen to Brett...he knows exactly what he is talking about.
  • wolfe10's avatar
    wolfe10
    Explorer
    Sep 12, 2014
    Actually, without records, I would make NO assumptions.

    But, first valve adjustment is not due until 30,000 miles.

    And, with that low mileage over 15 years, it is quite likely that you have contaminated fuel. Check your primary fuel filter for any sign of rust, algae (black precipitate or slime) etc.

    Also check all fluids for changing-- coolant, transmission, rear axle, etc. Cheap insurance.
  • Bucky1320's avatar
    Bucky1320
    Explorer
    Sep 12, 2014
    Good suggestions for sure. 26,000 miles and CAT has no service hits on it, so I can only assume that all service was done by independents.
  • wolfe10's avatar
    wolfe10
    Explorer
    Sep 12, 2014
    Clearly, intermittent voltage to ANY electronic engine will cause a number of codes/symptoms. So, I agree, start by verifying 12+ VDC to the engine computer AND a good tight ground (there is usually a ground wire from just below the ECM on the engine to good chassis ground.

    As far as performance issues, ALWAYS the first thing to do is replace the fuel filters. They are inexpensive and a clogged filter will materially limit power. This is most noticeable at higher RPM, as more fuel is being demanded. Clogged filters/reduced fuel flow is also hard on injection components, as the diesel is used to cool and lubricate them. Could it be other thing-- sure, but start with one that is relatively inexpensive and one that DOES cause issues in many coaches-- particularly those that have sat for awhile.

    You don't mention much about your rig-- how many miles are on it? Have the valves ever been adjusted. If you are not the original owner, I would call Caterpillar Corp with your engine serial number. If a Caterpillar dealer has done work on it, Caterpillar Corp can pull up that information for you: 877 777 -3126.
  • Mike_Hohnstein's avatar
    Mike_Hohnstein
    Explorer
    Sep 12, 2014
    New ignition switch might fix it all, first thing I'd throw at it. And remove and clean every ground cable, strap you can find, chassis, body, battery.
  • Bucky1320's avatar
    Bucky1320
    Explorer
    Sep 12, 2014
    The codes are:
    21 Sensor Supply Voltage Fault
    34 Engine RPM Sensor Fault
    49 Inlet Air Heater Circuit Fault
    71 Ignition Keyswitch Circuit Fault

    If there was a Magnum Chassis dealership local.....or anywhere....that would be an option. But I prefer to do all I can myself.
  • Mandalay_Parr's avatar
    Mandalay_Parr
    Explorer
    Sep 12, 2014
    You probably need to take it to the chassis mfg dealer for the cruise issue.
    They can also decifer the codes for you. A Cat engine dealer can do the codes too.
    Normally Cat just supplies the bare engine and the chassis mfger does all the rest.
    On diesels the max torque is at the lower rpms opposite of a gas engine.
    Your performance sounds pretty normal.

    Call me if you wish.

About Motorhome Group

38,705 PostsLatest Activity: Jan 23, 2012