Common Starting Issues in Trucking Applications---Part 2

Slow Cranking: For the starter to be cranking, the control circuit would have to be working. So, if battery and cable checks are within specification and the vehicle still cranks slowly, then it’s a slow cranking problem and it’s time to replace the starter.

Click No-Crank: Check the control circuit. If the starter does not contain an Integrated Magnetic Switch, or IMS, then a voltage drop test will need to be performed on the vehicle control circuit. If the starter does have an IMS switch function, then the technician will have to verify that the vehicle’s control circuit is providing voltage to the starter IMS.

No-Click No-Crank: When this occurs, power is not being sent to the solenoid, making it very unlikely that the issue is related to the starter motor. A diagnostic tool can help you diagnose the complete starting and charging system, including the alternator, batteries, starter motor and wiring. The diagnostic tool can perform a full system check in about 25 minutes, making it a great investment for your workshop. So in a poor starting environment, or when a starter motor has failed, what could be wrong?


Batteries – By now you should have tested your batteries and replaced any that were faulty. Don’t be tempted by the false-economy of leaving one poor quality battery in a bank of four. And you should look at your battery cabling, as this can often be less than optimum from new. In the diagram below, the top illustration shows the original battery cable layout, which results in the two inner batteries working hard and the outermost two never receiving optimum charge. In the diagram below (Pic 1) shows an easy solution to balance the workload of the battery banks.



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Common Starting Issues in Trucking Applications---Part 1

Cranking problems can be frustrating, identifying and correcting the root cause does not have to be. The first step is to identify the symptoms. In a cranking system, you can divide your symptoms into one of three possible troubleshooting categories:

Slow Crank: The Mitsubishi starter will crank, however, the engine RPM is too slow to start the vehicle.

Click No-Crank: The solenoid clicks but the starter doesn’t crank.

No-Click No-Crank: The solenoid doesn’t click and the starter doesn’t crank.
Once you’ve identified which problem you’re dealing with, then you can start to remedy it. For all issues, the initial troubleshooting is the same: you start with the batteries.

STEP 1 – Begin at the batteries: Charge the batteries and perform a load test on each battery in the battery bank. If any batteries aren’t up to spec they need to be replaced or you will shorten the life of the other batteries and compromise the health of the starting circuit.

STEP 2 – Perform a voltage drop test: Once the batteries pass your tests, perform a voltage drop test on the starter main cables. The starter voltage drop should be less than .5V total on the cranking circuit. This is an important step and is often the cause of a slow cranking complaint. Yet voltage drop also is a leading cause of click or no-click complaints because almost every vehicle manufacturer uses the heavy positive post, located on the starter solenoid, as a place to pick up the current used to supply the control circuit.

STEP 3 – Identify the specific issue: Until now, the diagnostic path has remained the same regardless of the complaint. Now is where you address the specific issue.

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How to Replace a Car's Starter Motor---Part 5

Remove the battery ground. Now you can go below and remove the wires to the Denso starter. There will be a fat wire from the battery or, if your car uses one, an external solenoid. There will also be one smaller wire, either a ring lug on a stud or a spade lug, from the ignition key. Older vehicles with points-and-distributor ignition may have a third wire to the coil, bypassing the ballast resistor. Don't get them confused.

Now get a socket and ratchet and probably an extension, and remove the bolts holding the starter to the block. You may also need to remove a heat shield, brace or sheet-metal cover to get everything loose. Don't drop the starter onto your head as the last bolt comes out; it's as heavy as a bowling ball.

Don't get out from under the car just yet. Mark one tooth on the ring gear with some spray paint or even chalk, and inspect every single one of the 140 to 160 teeth by turning the engine over with a big screwdriver for one full revolution. Seriously damaged teeth will require replacement of the flex plate or flywheel, which commences with removing the transmission from the vehicle. Fear of the necessity of this should motivate you to fix a balky-but-still-barely-working starter before it damages the teeth. Labor to remove the transmission and replace the flex plate or flywheel will be 6 to 8 hours, more if you have four-wheel drive. Add in the cost of parts and a ring gear replacement could easily reach a thousand dollars or more.

Take your old starter motor to the auto parts store and exchange it. Don't be surprised if the new starter bears only a faint resemblance to the older one. The industry has been transitioning to smaller, lighter gear-reduction starters that use a higher-speed motor coupled to a planetary gearset to spin your engine faster while using less current. The new starter will have grease already in places where it's needed, so no further lubrication is necessary or desirable.

Replacement of the new starter is straightforward, at least if your vehicle doesn't require shimming the new starter. Snug up the mounting bolts, reinstall any braces, covers or heat shields, and hook up the wiring. All you need to do now is reconnect the battery ground, take the vehicle off the stands and start 'er up.

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How to Replace a Car's Starter Motor---Part 4​​​​​​​

4. Bottom line, there should be 9 to 10 volts at the Delco Remy starter motor hot post when cranking. Don't forget to put the car in neutral or park and block the wheels so you don't run yourself over.

5. Battery cables okay? Try jumping—with jumper cables—directly from the battery positive terminal to the starter motor's solenoid post. If the solenoid pulls in and the starter turns over the engine, you've got a wiring problem.

6. If the solenoid doesn't pull in and energize the armature, try jumping directly to the motor's armature post, bypassing the solenoid. If the armature spins, the problem is in the solenoid or its wiring.

7. Don't forget that some antitheft systems will still disable the starter even if the crooks hot-wire the ignition key. And when something goes wrong with that alarm, you're stranded. It gets worse—it's usually difficult or impossible to disconnect the alarm, in order to keep the car thieves from doing so. Be prepared for serious reading of the factory shop manual or, if your alarm is aftermarket, a return to the alarm installer.

No More Excuses.

Regardless, you've determined that the starter is fried. Time to get to it. You might get lucky, especially if you have an FWD vehicle, and be able to swap starters from above the car. If not, the starter usually lives in a really remote location well underneath the car, somewhere near the side of the transmission. Don't try to do this on a hot car—which might seem to be superfluous advice if you can't even get it started—but invariably the exhaust system is nearby, and burns hurt. Also, protective eyewear is de rigueur, because you'll be dropping flakes of rust and underhood dirt from directly above your head into your baby blues. While you're waiting for the car to cool off, chock the wheels and jack it up a foot or so. Ramps will work, but I prefer a pair of sturdy jackstands. On the other hand, I've also been forced to do this in the middle of a muddy field by scooping out a trench to lie in.

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How to Replace a Car's Starter Motor---Part 3

1. Yes, there's a Mitsubishi starter motor hiding up there. On most front-engined vehicles like this Suburban, it's well and truly buried under and behind the engine and next to the transmission.


2. Prepare to get dirty and uncomfortable getting it out. Front-wheel-drive cars with sideways-mounted engines may have the motor mounted above the trans, where you can reach it from above.

3. If you have ramps, they should provide enough clearance. If you need to jack up the car, use jackstands and chock the wheels. Stuck off-road? Dig a trench under the vehicle to crawl into, which is actually not horrible if it's dry.

Is Your Starter Motor Really Bad?
Before you get all greasy under the car, here are some tips for diagnosing a bad starter:

If you twist the key and the dash lights come on dimly, the solenoid buzzes or clicks, or nothing at all happens, it may well be the battery or the cables, not the starter motor. Charge the battery. Your voltmeter should read at least 12.6 volts with no electrical drain on the battery and the charger disconnected for an hour.

2. Check the battery capacity. I use a resistance-type battery load tester. A good, charged-up battery should deliver 150 amps for 15 seconds without dropping below 10.5 volts, and should recover nearly to the aforementioned 12.6 volts within a minute.

3. If the battery checks out okay, look for poor electrical connections to the starter or solenoid, as well as the battery and chassis connections. Accept no more than a 0.5-volt voltage drop between the battery post and the starter hot post. Ditto between the battery negative post and the engine block.

How to Replace a Car's Starter Motor---Part 2

Saturday morning you give your battery and charging system a full investigation. Even swapping in the new battery from your other car doesn't help. Nope—the screeching has become the only symptom you can elicit. That banshee wail is the teeth on the starter motor's bendix gear clashing against the ring-gear teeth because it's not completely engaged.

The solenoid, or on some starters, just a threaded part of the armature, pushes the bendix gear forward an inch or so until it meshes with the ring gear, allowing the starter motor to spin the engine over until it starts. When the engine rpm exceeds the cranking speed, the bendix automatically retracts, preventing the engine from spinning the starter too fast.

At least that's how it works in theory. Starter motor failure is rarely caused by a blown or shorted motor itself—usually it's a problem with the bendix mechanism or the solenoid. And frankly, most people will never need to replace a starter motor for the life of their vehicle. Intrepid but underfunded Saturday Mechanics might actually dismantle a malfunctioning starter and repair it themselves. You can still find auto parts stores that can get you new bearings, brushes and bendix assemblies. Generally, I just exchange the old starter for a new or remanufactured one, because repairing one doesn't save much money. On the other hand, if you have a rare or hard-to-find starter it might be necessary to fix what you have. Usually, auto electric shops （Denso Starter Supplier) can rebuild or repair a starter with a bad armature, shorted field windings, bad brushes, a bad commutator, or even a bad solenoid if there is no alternative. Be prepared to wait a few days or more.