Lexus IS200 starter motor brush repair

This procedure is relevant to other Toyota planetary gear starters.

The exact factory procedure is under Starter Components in the TSRM

Symptoms of the problem:

  • No tick, tack from the starter solenoid when turning the key.
  • Tapping the starter with a stick while turning the key agitates the starter enough to start.

The starter solenoid has 1 power and 2 grounds: one ground to the body of the starter, and one ground through the starter motor. Both grounds need to be connected for the electromagnetic solenoid to pull in.

The problem is not with the solenoid itself, but with the grounding through the starter. This can be verified by:

  • Disconnecting the high current input to the solenoid input post
  • Disconnecting the link between the solenoid output post and the starter motor
  • Connecting ground to the solenoid output post
  • Connecting ground to the starter assembly body

Then power the solenoid signal +12v, it should pull in reliably every time.

Tapping the starter with a stick agitates the motor brushes to make better contact on the commutator, making a better ground through the motor. Based on these symptoms the brushes or commutator in the starter motor are worn out.

Pull the starter and dissassemble:

IMG_1460

Usually we start by taking the other end off, but here we can see the brushes are 100% finished. 2 barely protrude from the brush holders. Where did they go? That pile of graphite tells the story.

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The commutator is scored and filled with worn graphite. I wasn’t sure if this would be reusable.

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Cleaned off and sanded it down

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The minimum service specification is 27.0mm. This one is OK to be reused.

IMG_1472

Here’s the brush holder end. The brush holder assembly is replaceable and can be ordered from Toyota. This is for a 1999 IS200 with a 0.8kw starter. If yours is different check the catalogue

  • 1x 28140-70020 HOLDER ASSY, STARTER BRUSH
  • 2x 28142-70020 STARTER KIT (these are the negative brushes)

The brush holder assembly contains the positive brushes. The negative brushes are separate and have to be crimped on to posts on the field body. Details of this whole job are in the service manual.

MX83 Ignition switch contacts and starter relay mod

After identifying and replacing the starter solenoid contacts in my mx83 I still had intermittent starting problems.

Voltage drop at the starter solenoid, but not other circuits, indicates a fault in the starter solenoid circuit. When powering the starter solenoid directly from the battery with a test wire it pulled in hard without a problem.

Older Toyotas don’t run a starter relay, Instead they run all the starter solenoid power through the ignition and neutral switches. Over time the copper contacts degrade, the grease dries out, and the wiring goes high resistance. Once this occurs the circuit can’t deliver the 10-15A required to pull the solenoid in.

There are fixes for this:

  • Replace or clean the ignition switch
  • Replace or clean the neutral switch
  • Test all the wiring
  • Install a starter relay

All the detailed information for these is available elsewhere, I’ll post links and list some pointers:

Replace or clean the ignition switch

Unless yours is totally ruined (cracked case or worn through contacts) don’t replace it.

This section is now updated with my own photos and more instruction

  1. Take the ignition switch out
  2. Pry each leg of the white case up very gently, it’s brittle.
  3. Note: Be careful when disassembling, the black plastic carrier is loaded with springs and balls for the detent of the switch. It shoots apart. You don’t need to take it out of the housing.
  4. Take the contacts off the carrier
  5. Wipe the contacts (including the posts) clean with brake cleaner or similar
  6. Lightly sand the contacts and apply fresh dielectric grease
  7. Clip back together and reinstall

Notes:

  • Don’t worry about putting match marks on the case – it can only clip together one way – that’s why all the clips/legs of the case are different sizes.
  • Don’t worry about the orientation of the contact discs – between the square and round locating tabs they can only go in one way.

This helped a lot, but didn’t 100% solve my problem.

Replace or clean the neutral switch

When they go bad jiggle the shifter in park or neutral and see if it starts. It can be cleaned like the ignition switch, but it’s under the car and will need the shift linkage removed to get it out. Refer to TSRM for lining up the switch when reinstalling.

Although I could not find a specified resistance in the TSRM, my resistance was low and the problem persisted with the switch bypassed.

Test all the wiring

Make sure you’re getting power at the solenoid. Visually inspect the starter and gearbox wiring harness for damage. The next step would be to pull out your dash. Unless you have no power at the solenoid, don’t hunt wiring.

Edit: US spec cars have an immobilizer and a starter relay. The immobilizer switches signal ground on the relay. The wiring diagram (TEWD) is available online.

Install a starter relay

The mx83 is conventional, but it will need to pass a small amount of current through the relay coil, as the ECU’s neutral switch sense circuit normally grounds through the starter coil. I used a normal automotive relay and it was fine.

starter-relay2
Image from linked article

http://www.sq-engineering.com/index.php/tech-articles/relay-upgrade-for-a-starter-motor

  • I like how short the wiring is and the grounding of the relay.
  • I recommend a fused relay. I used a 30A rated relay with an inbuilt fuse holder, swapped down to a 20A fuse.
  • Put it in a position where it’s not going to get wet, oily, or dirty
  • Observe the high current feed into the relay is unfused, make sure the connector isn’t going to slip off or shake loose.
  • Use fully insulated spade connectors which fit super snug on the relay and solenoid terminal.

MX83 Cressida starter solenoid contacts

My starter solenoid contacts wore out. Here is info for a Cressida/Crown/Supra with a denso starter.

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Although the denso starter solenoids are fairly common, I wanted to make sure I was ordering the right parts. Many rebuild kits on ebay and amazon are vague in their application list, and vague is never good.

I checked my part number of my starter solenoid as 28150-41060 as used on 5M, 6M, 7M, RZ engines. As I couldn’t find a rebuild kit listing exactly that part number, I took it apart and here are the dimensions I measured:

  • ~20.65mm Plunger body diameter
  • ~36.8mm Plunger ring contact diameter
  • ~96.65mm Overall rod length including top hat
  • 8mm diameter terminal posts outside the body of the solenoid
  • Extended wing (‘C’ shape) contacts – ~21.5 mm wide. Type 1 on the photo below:

s-l1600

This is valid for 28150-41060 only. If yours is a different P/N I encourage you to measure it – you need to take it apart anyway. When getting a kit, make sure to get one that includes a plunger, as the ring on it is a wearing contact too.