Title: Intermittent No-Crank / Weak Crank – Key Pressure Changes Behavior (’98 LX470)

[tsszen243]

Hey all, looking for some experienced input before going further.

Vehicle: 1998 Lexus LX470, ~227k miles.

I’ve been chasing an intermittent starting issue that’s evolved over the last couple weeks.

Symptoms:

• Sometimes starts perfectly
• Sometimes weak crank
• Sometimes no crank at all (dash lights and accessories on)
• Very often starts strong on the second key attempt
• Key pressure changes the outcome

Here’s the repeatable behavior that feels important:

• If I push the key fully inward and turn, it almost never starts
• If I insert the key normally and just turn, it starts more consistently
• First attempt is often weak or dead
• Second attempt almost always cranks strong and fires

Examples from today:

• Morning start: first attempt weak crank, second attempt strong → started
• Later start: first attempt no crank, second attempt strong → started

Electrical checks so far:

• Battery voltage at rest (overnight): 12.75V
• Voltage during crank attempt: drops briefly to ~11.5V, then recovers
• After start / charging: ~13.8V
• Battery terminals clean and tight
• Grounds visually inspected
• No clicking from starter relay — weak or no crank on first attempt

Symptoms do not appear heat-related at this point.

Initial diagnosis thoughts:

I know starter contacts are common on these trucks, and that was my initial direction. However, the key pressure sensitivity combined with weak → strong cranking on immediate second attempts is making me rethink that.

Currently leaning toward ignition switch (electrical portion) or lock cylinder wear, where pushing the key inward slightly misaligns the switch and prevents full START contact. Second attempt seems to seat the contacts better and pass full voltage.

Questions for the Mud brain trust:

• Does this symptom pattern line up with a failing ignition switch on the 100-series?
• Has anyone seen key pressure specifically affect crank/no-crank behavior?
• Any recommended voltage or continuity tests at the ignition switch connector before replacing parts?
• Would you still pull the intake and do starter contacts first, or rule out ignition switch before going there?

Appreciate any insight — trying to diagnose this properly before throwing parts at it. I’m very much a novice when I comes to 100 Series maintenance and would feel much more comfortable doing the ignition switch as opposed to the starter/connectors and removing the intake manifold. Thanks!

 

[excessive]

there are 2 known issues on early 100's that you might want to research

1. Ignition rod can fall apart or break
2. Fuse box / EFI relay contact melting issue