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Emergency Troubleshooting Procedures - FAQ Item (Recommend Keeping Copy in Truck)

Discussion in '80-Series Tech' started by Romer, Oct 18, 2006.

  1. Romer

    Romer fatherofdaughterofromer Moderator

    Sep 14, 2003
    Centennial, Colorado
    For updates or revisions, please PM me, nuclerlemon or semlin

    The below is a troubleshooting guide if your in the boonies to help isolate a non starting vehicle problem. This is a compilation from forum members, specifically RavenTai, KliersLC, Landtank and Beaowulf. This will not catch each and every problem, but if your vehicle won’t start here are a few things you can try.

    Recommended standard tools:
    • Pliers, Spark plug removal tool, screwdrivers and wrenches fund in tool kit with tire tools in back on the left side
    • Emery cloth or other to clean battery connections (Wire brush)
    • Voltmeter
    • Timing light or other tool to validate spark
    • OBD II Scanner (Not reader) for 96 and up.
    Scenario 1:
    Turn key, no cranking of engine:

    Possibilities -Cables, Battery or fusible link
    * Inspect Battery cables.
    * Inspect/Check fusible link (see below). You can use a voltmeter to verify 12V at alternator or starter. Verify ground to chassis with volt meter (<1 ohm).
    * Clean battery terminals and inspect fusible link (see below). Jump vehicle if necessary, try with another battery if available.. Note, if contacts are corroded, jumping may not work. Also, poor quality cables may not be able to effectively jump vehicle.

    There is also the possibility of the Neutral Saftey switch or a common problem of the connector having coroded wires at the Transmission. See this thread for my troubleshooting of this problem on my daighters truck. You can sometimes test this by wiggling the connector

    Scenario 2:
    Turn key, click or many clicks (no crank):

    Possibilities - starter and/or low battery voltage.
    * Clean battery terminals and jump vehicle, if there is still only a click, keep trying, it is likely it will fire after 10-15 tries
    * Some have tapped starter with hammer with success.

    Scenario 3:
    Turn key, engine turns over but does not run:

    Possibilities - Lack of spark from ignition system (Distributor) or lack of fuel. Note: Fuel + Spark + Compression = engine that starts, must have all 3.

    * Compression does not instantly disappear without letting itself be known (big noise, big hole in side of the block etc).
    * if no check engine light when the key is turned to on then the fuel injection system, more specifically the ECU is not powered.
    * Check to see if there is spark via one of the three methods
    o If there is a spark plug removal tool in the tool kit, pull a plug (#1 is easy) reinsert the plug into the plug wire and hold it against the motor so the plug gets ground, have some one crank the engine, you should see spark
    o If you have access to a timing light you can check for spark without having to remove the plug
    o Or, spark tool such as one from Harbor Freight:
    * Check to verify Fuel pressure is present:
    o Quick test for fuel pressure is to remove the return line from the fuel pressure regulator, it is a spring clamp right on top and easy to get to, all you need is the pair of pliers from the tool kit, after the line is removed crank the engine fuel should come out of the pressure regulator, if it does not you have a fuel problem, out of fuel, bad fuse, bad fuel pump relay, bad pump
    o to find this line find the fuel injectors nestled in the valley between the intake plenum and valve cover, at the top of the injectors is the fuel rail it is cast aluminum, follow the fuel rail all the way to the front where you will find a tallish flying saucer looking devise, that is the fuel pressure regulator,
    o where the pressure regulator threads into the fuel rail is high pressure fuel, at the top is a vacuum line, in the middle is the fuel pressure return that is the line we want to remove to check for fuel flow.
    o You might want to remove the gas cap to relive any pressure so less fuel will come out when you remove the line.
    o And of course be safe around fuel, For instance do the spark check first before you cover the top of the engine in fuel, also try to get as little on you as possible, if you do get fuel on you wipe it off ASAP, no need to turn a roadside repair into a visit to the local burn unit and a totaled cruiser.
    o Another option is using the OBD II port with the ignition on a 96 and up. You need a scanner that monitors real time data.
    o Check Fusible Links per below.
    o (If other tests show no fuel present) Potentially fuel relay (located in fender) contacts are corroded. The proper way of cleaning a relay is with a burnishing tool. This is like a ultra fine very thin file specifically for relay contacts. Good luck finding one, I did and it was an hour away. So plan B, (not -B-), is to use an old trick I (Landtank) was taught back when I first started in field service.
    What you need to find is a new match book. Cut the strike area out of the book and you have a very good substitute foe a burnishing tool. You slide the striker in between the contacts and the in a filing motion clean the contacts. DO NOT add any addition force to pinch the contacts closer!!! Once done on one contact flip and rotate the striker to clean the other contact in a clean area of the striker.​

    a blowing EFI Fuse Story

    Probably Good voltage but no engine crank: cylinders filled with oil
    * Pull efi fuse and plugs and then crank engine, make big mess, install one plug at a time until it will turn over with all installed, reinstall EFI fuse and prepare for a large cloud of smoke.

    Fusible Links and Relays
    Below is a list of fuses and fusible links and relays critical for engine run, this is taken from a 96 LX EWD, should work for 95-97 I would imagine 93/94 would be similar.
    There are three fusible links near the positive post of the battery, all three are needed for the engine to start and run, they look just like wires as that is basically what they are, they are intentionality weak wiring that melts with too much current, a blown one may melt in half insulation and all and smoke a lot, or the insulation may just look bubbly and melted on the surface but still look attached, or may look just fine from the outside but be severed inside
    The three come from Toyota as a set, all three are replaced at the same time, they are cheap, everyone should have a set in their glove box, and everyone should also carry an assortment of regular blade fuses also,

    "Main" Fusible link, critical as it is upstream of the 15A EFI fuse under the hood, you can test this one from the drivers seat by turning on the radio, headlights, ac/heat fan, defrost, stop light, tail lights and telephone, if any of the above work then this fusible link is good,

    "AM1" Fusible link, critical as it is upstream of the ignition switch and provides the power for to the starter solenoid, you can check this one from the drivers seat by checking the horn/hazards, dome light, diff locks, rear heat, turn signals, cigarette lighter, or wipers,
    If you have the hazard & horn but none of the others check the big 50A AM1 fuse in the under hood fuse box (50A AM1 fuse not to be confused with the AM1 fusible link) Might not be a bad idea to stock a 50A fuse incase the big AM1 fuse blows

    "AM2" is probably the most engine centric, it provides power to the ignition switch, the injectors, the igniter, the ignition coil, the distributor, and the alternator control system, if you get the yellow light on the volt meter with “key on engine off” this fusible link is good, ​

    There are only three critical regular sized fuses required for the engine to start and run
    15A EFI located in the under hood fuse box
    7.5A Ignition located in the fuse box at the drivers knee
    15A ECU-IG located in the fuse box at the drivers knee
    You should stock at least some 15A and 7.5 amp blade fuses if not a complete set, but those two sizes are what you need to limp home.

    Critical Relays
    EFI main relay, under hood fuse box & Circuit opening relay, turns fuel pump on and off, located behind the drivers left kick panel, Both of these relays are the same part number, 90987-02004, you should have one in the glove box.

    Starter cut relay, for theft deterent, usually drivers left kick panel, starter cut relay probably depends on witch alarm you have, some trucks may not eve have this relay.

    Fuel pump relay, changes the speed of the fuel pump, bolted to the drivers side inner fender near the back on the edge of a large opening. part number 28381-16020, not as cheap but roadside repairable per Ricks instructions, so you do not have to stock this one.


    If you have a stock of all of the above in your glove box none of the “consumable” electronics can keep your 80 from running.
    Last edited: Jun 26, 2011

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