# '89 HB - Issues while driving



## dandygarage (Mar 4, 2018)

Hello! New to the Nissan forums, pretty new to the car scene in general.

I recently purchased a 1989 Nissan Hardbody that was billed as completely mechanically functional by the previous owner. Contrary to what he said in the CL ad, there's one major problem that didn't reveal itself until I was driving it home. Periodically while driving the truck will start to lurch forward, like what happens when a first time stickshift driver tries to take off. The RPMs fluctuate, the car continues to lurch forward and move sluggishly, then eventually stalls. Turning the car off and on, either while stopped or while moving, remedies the issue temporarily. 

Some ideas I've already gathered from the forums: Fuel pump failure, bad gas, fuel starvation caused by chunks of something in the fuel lines, fuel filter problems. Any additional input or things I could test for would be appreciated, as I'm already $1900 into the truck and would like to at least get it driveable before trying to daily/re-sell it. Thanks in advance


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## jp2code (Jun 2, 2011)

It sounds like you are in Fail Safe Mode, or commonly called Limp Mode. This is a condition the ECU creates whenever it fails to detect one of the signals from a sensor. The goal was to get owners to take the vehicles in to the dealership, where the sensor would be repaired. But, these trucks are so old now that most dealerships do not have mechanics who know how to work on them.

These trucks are pre-OBD2, so you cannot connect a code reader.

They do have a way to read codes, but it involves pulling the passenger's seat off (or, removing the bench seat if you have a truck like mine).

The ECU has a dial or a switch that signals the ECU. When you key is ON (but engine is OFF), it will blink once, pause, blink twice, pause, blink 3 times, pause, blink 4 times, pause, blink 5 times, pause, then start over at 1 blink. When you are on the 3rd blink, you want to turn the switch the other way to select "Diagnostic Mode 3". Once you are in "Diagnostic Mode 3", the little LED lights will blink to tell you what the codes are. To clear the codes, put the ECU into Mode 4 or 5 and turn the Key OFF.

I made a write-up on how to do it here:

[VIDEO] Checking Error Codes - Infamous Nissan - Hardbody / Frontier Forums


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## saudade (Apr 10, 2010)

Yep, pull the codes as listed above. On my 87, codes 23 and 24 required operating the shifter and gas pedal to eliminate.

Double check all electrical connections. I had a bad splice in a harness feeding the injectors that cause the engine to cut out around 2500 rpm.

Later, I found corrosion on the connector to the ECU under the seat that caused other problems.

Good luck


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