weird engine/electrical problem - help please

Have 93 4runner 6 cylinder auto.

About a week ago the speedometer started dropping to 0, the odometer stopped & cruise control kicked off. Other times the speedometer would bounce around & then go to 0. Then the problem would go away for a while. If it stayed off for over a couple of minutes then the engine check light came on. I was hoping the problem would move from intermittent to hard so I could take it to the dealer.

Tonight my wife came home and said its now worse. First the speedo stopped, then the engine check light (same as before), then the tach started bouncing around the engine reved high but truck stayed the same speed then it started surging/lurching. She said you could press the gas but it would only go slow, but the engine rev'd up!

So in to the dealer tomorrow. Any ideas? Is there a computer chip involved?

Reply to
neon
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Possibilities in the order of likelihood are the speed sensor in the transmission; speedometer head in the instrument panel; the wiring between the speed sensor, speedo head and computer; or the computer itself. Repair cost also happens to be in about the same order as likelihood of problems.

The check engine light came on because the computer detected the problem. The good news is that there is probably a trouble code stored in the computer's memory so the dealer will know where to start looking.

A computer chip is a component on a circuit board and rather than trying to diagnose and replace individual chips, the dealership will replace the entire component containing the board or chip.

Reply to
Ray O

I thought it might be something like your first three, but then the weird surging & tach problem made me think computer. But I didn't know if a 93 had a "computer" thanks well try to get to the dealer without a tow truck

Reply to
neon

All electronically fuel-injected Toyotas have computers. By the way, all modern vehicles have computers now.

The surging and tach problem is what made me think of the instrument panel, but a bad speed sensor can give the transmission fits, which could cause surging.

Reply to
Ray O

Took it in to the dealer (30miles). Had a portable phone & a tow truck #. It got me there without displaying the symptoms my wife described. But the speedo did its thing. And no engine check light!

It was scheduled in for Monday for timing belt & misc anyway.

Gave chief mechanic my note above. I'll report back, but have a bad feeling about this.

Reply to
neon

A 93 4-Runner did not have an OBD II system and would not catch a problem with the speed sensor or loose ground somewhere.

Reply to
Ray O
93 4runner V6 auto Dealer called yesterday. It's the speedo. (See below for part 1) $300 for new one & $375 for troubleshooting & installation. So said OK. Picked up today (and paid $1600 more for timing belt, belts, hoses, water pump, thermostat, anti freeze, plug wires and idler arm). Got 8 miles away & bam - same problem (but funny to have 3 kilometers on the odometer and a bright red needle!). So they had me sign a no charge work order, gave me a free rental car, said they would replace my old speedo, fix the problem and then we would settle up the bill. Was going to press for a refund and then start the clock again but decided not to fight the fight until it's fixed properly.

Will post again when resolved.

ps I've kept a spreadsheet on all repairs, and calculated running costs per year, based on my mileage. Would be interesting to compare major & minor probems with older 4runners.

"Ray O" wrote:

Reply to
neon

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